Amu Hinamori, the series protagonist, is student of Seiyo Elementary. Amu was seen as a cool and stylish girl and has become popular at school but what she really is is just a shy, gentle, docile, and extremely normal girl. The main reason for this misunderstanding is the trendy punk clothing her mother buys for her. One night she wished she was not the type of person she currently was, and on the next morning, three Guardian Eggs appeared.
During Character Change and Character Transformation her hair clip changes (Ran→Heart, Miki→Spade, Suu→Clover, Dia→Diamond) Her Character Transformation forms are named: Ran→Amulet Heart, Miki→Amulet Spade, Suu→Amulet Clover, Dia→Amulet Diamond. The characters Amu becomes are good at certain activities like Amulet Heart who is athletic, Amulet Spade who is good at Art and Crafts, and Amulet Clover who is good at cooking (all house-work in general).

The first to come out from Amu's Eggs. An athletic and honest character. Her hair is tied in a side pony tail. She has a pink sun visor, a red themed cheerleader outfit, and wears a heart shaped hair clip. Dislikes silence. During Character Change, Amu gains increased athletic abilities. Little wings appear at her wrists and ankles, which allows her to jump high and fly. Having a straight forward personality, Ran made Amu confesses her crush to Tadase on their first Character Change.
Amu becomes "Amulet Heart" when she Character Transforms with Ran. The clover decoration of her Humpty Lock changes to the color pink. Amu dons a pink themed cheerleader costume in this form. Her special move is "Spiral Heart" which is executed with the Heart Rod. When Amu does Character Change with Ran, Ran says "Hop, Step, Jump". Ran was seen on Peach-Pit's website before the publication of Shugo Chara!, volume 1.

A Guardian Character with an artistic flair. A cool, quiet character. Her hairstyle is a short bob cut. She usually wears a pair of half-cut pants, a sky blue beret with a spade on it, and a blue themed outfit. Miki has shown an interest in both Tadase's Character, Kiseki, and Ikuto's Character, Yoru. She comments that Yoru is cool and his tail is cute. This may imply the situation in Amu's heart.
The main ability after Character Change is an increased artistic sense but that power is recklessly abused.
Amu becomes "Amulet Spade" when she Character Transforms with Miki. The clover decoration of her Humpty Lock changes to the color blue. Amu wears a white frilly blouse with a pair of light blue pants. She also wears long, striped stockings and a garter belt; all in a blue themed costume. Her special move is "Colorful Canvas", where she paints with a giant paintbrush. Miki says "Drew, Draw, Drawn" during a Character Change with Amu.

A Guardian Character skilled in baking sweets and doing house work. A "my pace" character that is prone to silly mistakes. She has short hair with the sides grown long, curling inwards. She wears a bandanna on her head with a clover shaped hair clip and a green theme maid outfit. Dislikes caterpillars. Amu gains an improvement in cooking during Character Change. Magical abilities like summoning large amounts of whip cream is also observed. In addition her speech and behavior becomes more lady-like. She has a habit of ending her sentences with "-desu" in the Japanese version.
Amu becomes "Amulet Clover" when she Character Transforms with Suu. The clover decoration of her Humpty Lock changes to the color green. She wears a green themed balloon skirt maid costume. Her special skill is "Remake Honey", a restoration type skill. Suu says "Chip, Syrup, Whip Cream!" during a Character Change with Amu.
Ran's, Miki's and Suu's Character Transformations all share another special skill, "Open Heart!". It is a skill that cleanse X eggs and X Characters.

Dia is Amu's fourth Guardian Character, with a musical flair. She became an X egg, and then hatched as an X Character in Chapter 17, after being discovered by Utau. Shortly after this, the character that emerged performed a Character Transforms with Utau, becoming 'Dark Jewel', and made a reappearance in Chapter 25 in a fight against Amulet Devil. Her special move with Utau was 'Shining Black', in which a dark light attacks the opponent. This Character Transformation has a defect, however, as Utau is not Dia's true owner; the Character Transformation dissolves quickly after it forms.
As Amu does not know Dia's real name, and still does not, as of Chapter 26, she just calls her 'Dia', a shorter form of 'Diamond'.
Dia became an X egg because of the change in surroundings, like Kukai graduating and Nadeshiko studying abroad. Usually X eggs form because of 'problems in the owner's heart', which shows that Amu has changed throughout the series from her inapproachable self to someone who socializes easily.
In Chapter 25, Amu convinces Dia that she can change, and so the 'X-mark' was lifted, sparking a Character Transformation, and making both the lock and key react. At the beginning of Chapter 26, Amulet Diamond was formed. Amu wears a futuristic outfit, in the style of an idol with lots of pleats, and pigtails, with a white headband. The Humpty Lock shines yellow.
Dia's true form differs from her X-form—her true self is portrayed as a rather giddy and excited character, much like an idol may appear, whereas her X-self was often seen as inapproachable. Her outfit changes from a 60s style dress, to a two piece with white boots. Her hair, which was at first portrayed as a 60s-style ponytail, became pigtails—both hairstyles included incredibly long hair, much unlike Amu's other characters. She has red-hair and orange-eyes.
Dia went back into her egg for slumber after transforming with Amu in chapter 26.

A kind-hearted and mature boy the same age as Amu who serves as the K-Chair (King's Chair). His alias is "Prince", and he is Amu's love interest. Whenever he is called "Prince," his character changes into a violent, egotistical king who wishes to rule the world. Because of this, he does not do Character Change with Kiseki unless it is absolutely necessary. Actually, he too is a shy person and is not a public speaker. Because of this, he wished to become another, stronger character, much like Amu. He lives in a traditional Japanese house. He had a precious dog named Betty (name learned in volume 2 of the manga) who died recently, and is still upset about it.
He, along with the other guardians, tried to get Amu to join because of a prophecy about a girl who will appear with three Guardian Eggs.
He claims to have a crush on Amulet Heart. He once also said that he loved Amu because Amulet Heart is her "self that she wants to be". At first he is about the same height as Amu, but as the story progresses, he grows taller.
At one time he lost confidence, as he could not seem to find the Embryo at all. He was then affected by the Black Diamonds CD, causing Kiseki to change to an X egg. Amu helped him out of this crisis and he is now able to Character Transform with Kiseki, becoming Platina Royale.
There is a point in the manga where Tadase reveals that he was once childhood friends with Ikuto and Utau.

The graceful but somewhat enigmatic former Q-Chair (Queen's Chair), who is the same age as Amu. When Amu rejected the offer to join the Guardians, Nadashiko tried many ways to convince Amu; One of those was to bribe Amu with photos of Tadase sleeping .
It was revealed later on in the manga that Nadeshiko is a boy and his real name is Nagihiko. It is the rule of the Fujisaki family that the males are trained to become oyama (male actors who plays female parts in kabuki). That is why Nagihiko wears female clothes and goes by a female name. He is currently studying abroad in Europe to make his dancing "complete."
In chapter 27, Nagihiko is shown with the first K-chair and Kukai. The First King has decided that Nagihiko will serve as the interim Jack, since Kairi left at the end of Chapter 26. Kukai is one of the first people other than Nagihiko's family and the first King that know his secret.
In the anime, Nadeshiko is fully female and her family runs a grand nichibu school. She sticks strictly to her practice schedule, but makes exceptions when it concerns her friends, particularly Amu.
He has yet to do a Character Transformation with Temari, however his character after Character Change is a battle-hungry yakuza type who speaks in Hiroshima slang and carries a naginata. In all, he is good friends with Amu, and he looks over and supports Amu in her love life.

The upbeat and energetic former J-Chair (Jack's Chair), he is one year senior to Amu. As the captain of the Soccer Club, he is athletic and has good reflexes. Once, in the school magazine, he and Amu are mistaken to be a couple as a student got a picture of him holding Amu after she came out of her Character Change and lost her strength. He has graduated, which is the reason he has been replaced. Saaya appears to have a crush on him, as when she saw the picture of him with Amu, she was furious. Through the power of the Humpty Lock, he and Daichi managed a Character Transformation once, forming "Sky Jack." The words 'Kick, Stack, Trap and Shoot!' spark his Character Change.

The childish and a bit immature girl serving as the A-Chair (Ace Chair), she is one year junior to Amu. Yaya likes the sweets baked by Nadeshiko. Her hair is tied in pigtails with a big ribbon. She does not know how to swim. She is also a ballerina, though a rather clumsy one.
She has newborn baby brother named Tsubasa, who, she claims, gets all her parent's attention.
Her Character Change character is a baby that uses a giant rattle as weapon; influenced by the "baby" character, she has a crybaby personality. The words 'Pretty, Cutie, Love Baby!' spark her Character Change.

The girl serving as the new Q-Chair, she is the same age as Amu. Rima is a short, cute and beautiful girl with a selfish personality. She is well-liked among male students and disliked by female students, such as Amu. She feigns crying to deceive people. At one point of the manga, while looking for X Eggs with Amu, she Character transforms and destroys one unnecessarily.
Her Character Transformation with Kusu Kusu is called "Clown Drop." When she does Character Change she becomes a gag character which she dislikes. The words 'Bala-Balance' spark her Character Change.

The boy serving as the new J-Chair. He is tall but actually he is two years junior to Amu. He prepares for Guardian's activities. Though the youngest, he is capable so Amu and Yaya call him "class president". He wears spectacles.
He is actually Yukari Sanjou's younger brother sent to spy on the Guardians. He chooses to switch sides, after Amu convinces him he is a good person, to fight and purify the X eggs. He seems to have a slight crush on Amu. At the end of chapter 26 he leaves saying that his job at their school is done, but not before declaring his love for Amu saying that he shall return for her when he has become a man. He also declared a rivalry toward Tadase.

A boy who wants the Embryo. On Character Change, he grows cat ears and his hand turns into a paw with metal claws. This form is known as Black Lynx. During Character Transformation, he uses a claw-like glove and his whole suit changes. At first he is called "Nekomimi hentai cosplay otoko" ( lit. perverted cat-ears cosplay guy) by Amu. He can play the violin. Like Amu, Ikuto too has sensitive ears. He possesses the "Dumpty Key". He is Utau's elder brother. He refers to Tadase as "Kiddy King".
He signed a contract with Easter and is looking for the Embryo, an egg that will grant any wish. Its because of that he becomes an enemy to Amu, but privately he helps Amu in the shadows. In the latest chapters, his relationship with Amu has taken a turn for the better. He has even said that he is "interested" in her. When Utau forcefully kissed him, he thought Amu got mad and asked her if she wanted a kiss.

A 14-year-old junior high student idol. She sings in plays. Lunatic Charm is the name of Iru's Character Transformation, during Character Transformation and Character Change Utau grows devil wings. The other Guardian Character, Eru, is now with Amu in the place of Dia. The gentle Eru seems to be treated badly, Eru performed Character Transformation with Amu, becoming Amulet Angel and it surprised Utau.
She is actually Ikuto's sister, Utau Tsukiyomi. She has a brother complex and chases any woman near Ikuto and calls them "bugs". Whenever she enters Ikuto's sight, she disables her Character Transformation and by all means tries to please her brother. At one time, through the power of the Humpty Lock, she did a Character Transformation with Amu's Dia Guardian Character, thus becoming Dark Jewel.
She is the vocalist of the indie band "Black Diamonds" which is produced by her manager, Yukari Sanjou. She also has feelings for her brother and even forcefully kissed him once.

Former staff of Easter Company. In order find the Embryo, he joined Seiyo Elementary and became in charge of Amu's class in the guise of a ditzy but kind-hearted teacher. His dream when he was a child was to become a robot engineer but when his mentor quit, because of his ailing wife, and his parents opposed the idea, he lost sight of his dream and became a twisted person. But he recovered with help from Amu and Suu. He resigned from Easter Company and officially become the teacher in charge of Amu's class. A running joke is that he calls Amu; Himamori meaning "leisure time".

Staff of Easter Company. Utau's manager, was competing with Nikaidou to see who is the first to find the Embryo. Seems to have a past relationship with Nikaidou.
She came up with a new project "Black Diamond" to at the same find the Embryo and mass-produce X eggs. The CDs of the band were freely distributed and the people listening to it will have their Eggs removed by force. As the band became more famous their song is slated to be released to the Internet together with the unveiling of the band. In Seiyo it is branded as a cursed CD. Kairi snuck the CD into Tadase's bag. When Tadase listened to it, he became infected causing Kiseki to change into an X egg, but Amu came and saved him.

Has only been mentioned and is yet to appear. The people of Easter Company refer to him as "Gozen" and his real name and gender are unknown. Ikuto refers to Gozen as "the greatest person in Easter" so it could be possible that Gozen is the company president. He promised the company employees a successful career if they can present him the Embryo. For what purpose he entrusts the Easter Company to find the Embryo is unknown.

Kiseki is Tadase's Guardian Character. He looks like a mini Tadase with different-colored hair. He is extremely egotistical, loves to dominate, but also has tsundere characteristics. He is always trying to outshine Yoru. His bearing is that of typical "king's fashion", complete with crown and mantle. Kiseki also occasionally calls meetings that require all the Guardian Characters to gather. In volume one, Miki seems to have a crush on him, saying he is cool. Kiseki likes to give orders but does not like to obey. Suffers from pollen allergy like Tadase.
Kiseki can do Character Change with Tadase. When this happens, Tadase gains a golden crown and king’s scepter. The only reason he usually Character Changes is to help Tadase become confident and if Tadase is called ‘prince’.
After the "Black Diamonds" incident, he became able to Character Transform with Tadase. Tadase becomes "Platina Royale" and used the special skill "White Decoration", a skill thought to be a restoration skill.

Temari is Nadeshiko's seemingly elegant Character. She is considered to be very girly and is always complaining about getting her kimono dirty, which always ends up annoying Daichi. Her hair tied in a ponytail with hair decoration in the shape of sakura flowers. She is skilled in handling the naginata and dislikes getting muddy.
Temari has the ability to perform Character Change with Nadeshiko. Nadeshiko then becomes battle hungry, often over little things like getting hit with a ball. Temari herself seems to have an anger problem. Says "Chin, Ton, Shan" during Character Change.

Pepe is a baby-like Guardian Character that belongs to Yaya. She always has a pacifier in her mouth, wears a full body baby outfit, and wears her hair in pigtails. When either she or Yaya get hurt or something goes wrong, both of them will begin to whine and cry in unison. Pepe could be described as a crybaby; however, upon further inspection may be described as somewhat sarcastic. Appears to enjoy being at the centre of attention, and playing childish games, such as piggy-back rides.
When she and Yaya perform Character Change, Yaya receives a baby bib and a giant rattle that she uses to squash or hit opponents with. Yaya says "pretty, cutey, love baby" during Character Change. Through the power of the Humpty Lock she is able to Character Transform with Yaya.

Kukai’s Guardian Character is Daichi. Daichi is very good at sports and cannot seem to sit still. He was born when Kukai wanted to do many sports but had to choose. He wears a sweatband around his head, shorts, and a sporty T-shirt. When Daichi and Kukai do Character Change, Kukai becomes even more athletic and gains a star clip for his hair that looks like the same star on Daichi’s head band. Daichi was able to Character Transform with Kukai once, resulting in "Sky Jack".

Kusu Kusu is Rima's Guardian Character. She wears a full-body clown suit and has a star drawn under one eye and a tear drop under the other.
During Character Change, Rima has the same marks under her eyes. Rima becomes "Clown Drop" on Character Transformation with Kusu Kusu. In that form Rima wears a clown costume with a ballet tutu. Her special move is "Juggling Party".

Kairi's Character. Musashi's overall look is that of a samurai of ancient times, his face and hairstyle look similar to Kairi's, except for an additional chonmage. Also wears spectacles like Kairi. When he Character Tranforms with Kairi they become "Samurai Soul"

Ikuto's Guardian Character, Yoru, has cat-like features. He wears a pair of paw gloves and boots and dresses in punk fashion style. Yoru has a freedom loving stray cat image and often wanders around wherever he pleases without staying with Ikuto. Yoru loves to tease and annoy Kiseki, who in turn tries to do things only Yoru can do, like climb on buildings and railings. He also seems to be scared of dogs.
When Yoru and Ikuto perform Character Change, Ikuto grows cat ears and a tail. In Character Transformation, they become "Black Lynx". Ikuto wears a spend-like outfit, has cat ears and a tail, and uses a glove with metal claws. In volume two, Miki seems to like Yoru as well as Kiseki, though, has more compliments showing she has more of a crush on Yoru than Kiseki.

Iru is Utau's first Guardian Character. She has short, dark hair and devil wings, tail, and horns. She wears a two piece skirt and top that seem to come on as if they were bats. Mean, unkind and dislikes nagging. When she and Utau perform Character Transform, Utau sprouts bat wings and many wing shaped accessories. Her special move in "Lunatic Charm" form is "Nightmare Lorelei". In chapter 25, Iru does a Character Transformation with Amu in order to try and save Utau and becomes "Amulet Devil".

Eru is Utau's second Guardian Character. Has an angel appearance. Eru is gentle hearted and seemed to be treated badly. Eru left home and is now in the care of Amu. She uses English words like "wait" and "shut up" in her speech. Likes to nag, dislikes meanness and unkindness.
Eru performed a Character Transformation with Amu once, resulting in "Amulet Angel", which surprised Utau. The clover decoration of her Humpty Lock changes to white color. Her special move is "White Flag". As Amu is not the real owner the Character Transformation quickly dissolves after it forms.
Eru finally performed a Character Transformation in Chapter 26 with Utau, forming Seraphic Charm. Utau wears a typically angelic dress in a Sweet Lolita style. Shortly after transforming, Utau helps Amu purify the X eggs.

An egotistical girl who is jealous of Amu in every way possible. She is in the same class as Amu, and shows off whenever she gets the chance (ex: professional drawing skills; undergarments). It is said that she has a crush on Kukai. However, in the anime, she had a crush on Tadase before having a crush on Kukai.

A spiritual fortune teller. Hasa praised fortune telling column in "Housewive's Knowledge". Actually she dislikes the occult. She is 54 and likes miso peanuts. Her spiritual sense is so strong that she is able to see the Guardian Characters.

Manages the planetarium as a part-time job. Artist of the artbook "Kokoro no Tamago" (The Heart's Egg). There seems to some mysterious parts in his book. Looks similar to Tadase. At first he is thought to hold the Humpty Lock. A cat lover and has a liking for Ikuto's cat ears.