Kouichi Aizawa

The Nabari no Ou anime and manga series features an extensive cast of characters created by Yuhki Kamatani. The series takes place in a modern-day Japan where the ninja world of Nabari (隠の世?, lit. World of Concealment) is hidden from the surface world, a name given to the world unaware of Nabari. The series' storyline follows Miharu Rokujou, a 14-year-old student who unknowingly possesses a powerful secret art within him, and his introduction into Nabari upon his power's activation.

The protagonist of the series Miharu Rokujou remembers nothing of his childhood and lost his parents at an early age. However, he is not concerned by this and strives to live a normal life. This plan is compromised when Miharu is attacked by real ninja and Koichi Aizawa and Tobari Kumohira come to his aid. There, Miharu learns about the hidden ninja world of Nabari and the Shinra Banshou, a powerful secret art containing all of the world's knowledge, which resides inside of him. This secret art is so powerful, the possessor is revered as the King of Nabari and is sorely coveted after. To protect himself, Miharu is forced to join his school's Nindō club managed by his two protectors. Kumohira vows to find a way to remove the secret art from Miharu. Until then, Kumohira, Aizawa, and Raimei Shimizu, a samurai from their ally the Fuuma Village, must protect Miharu from the Grey Wolves, a squad of elite ninja who lead the search for the secret art, and foil the Grey Wolves' attempts to gather each ninja village's kinjutsushō (禁術は?, lit. Forbidden Technique).

During the Sengoku period, Banten (萬天?) Village was a dispatch post of Iga Village. After the creation of the kinjutsushō Engetsurin (円月輪?, lit. Circular Moon Ring), it was considered to be an independent village. It was always small and is currently on the verge of extinction. Its members are known as the conservatives of the Shinra Banshou, Nabari's most powerful and coveted secret art. There are three Banten ninja: Miharu Rokujou, Tobari Kumohira, and Koichi Aizawa. Miharu is the possessor of the Shinra Banshou. Aizawa is one of Miharu's classmates. Although he seems to be a normal 14-year-old, he was originally an owl who became immortal after a former possessor of the Shinra Banshou experimented on him. Tobari is Aizawa's and Miharu's teacher in the front world. The village has no leader throughout the duration of the story's events. In the anime adaptation however, Tobari Kumohira is acting as the temporary leader. The Engetsurin's effect and whereabouts of the kinjutsushō are known only to Tobari. Although it has been seen in the manga adaptation in the recent updates, it has only been used once during the anime adaptation. It is located on a silver cuff on Kumohira's ear and has the ability to restore memories. The kinjutsushō is so powerful that it is able to restore memories to people who did not have the memory to begin with.

Miharu Rokujou (六条 壬晴, Rokujō Miharu?) is an apathetic 14-year-old middle school student and protagonist of the series. Although Nabari's most powerful secret art, the coveted Shinra Banshou (森羅万象, Shinrabanshō?, lit. All Things in Nature), is literally written into his body and he is venerated by all of Nabari's ninja as king, Miharu cares little about his gift's profound merits. His only goal is to inherit the family's okonomiyaki store. To protect those around him from getting hurt, he acts indifferently although he is not averse to acting in a rather innocent and cute manner to get what he wants. Miharu actually yearns for love at heart. After Miharu meets Yoite and promises to erase him in exchange for his friends' lives, his indifference begins to sway as his concern starts to revolve around Yoite. As the bond between them tightens, Miharu begins to wish for Yoite's continued existence, and offers to use Shinra Banshou to save him when Yoite collapses in a near death state from overuse of Iga Village's kinjutsushō Kira. However Yoite dissuades him from doing this and dies before the erasure can transpire. However the Shinra Banshou spirit comments that Miharu fulfills a wish of his own although he fails to erase Yoite's existence. After a one month rest, Miharu wakes up without any memories of Yoite, although he vaguely recalls erasing a person. He is voiced by Rie Kugimiya in Japanese and Brina Palencia in English.

Kouichi Aizawa (相澤 虹一, Aizawa Kōichi?) is Rokujou's seemingly 14-year-old classmate who studies Nindō under Kumohira. He is normally portrayed with an energetic attitude around other people, becoming serious and relentless when it comes to ninja duties. He is fascinated with death as a result of his immortality. His immortality is attributed to the holder of the Shinra Banshou during the Edo Period, who was a medical practitioner who experimented with placing the wisdom of the Shinra Banshou into animals, since humans usually died. He and Shijima Kurookano are the only survivors of the experiments and gained immortality; they believe that their mission is to observe the end of Nabari. This implies that Kouichi, and subsequently Shijima, are at least a century old. Kouichi's ultimate goal to have the Shinra Banshou release him from immortality and ensure that another immortal being or "monster" like himself is never created again. They are together referred to as the Hakutaku (白澤?) The Aizawa household are descended from Fuuma ninjas and are native Banten ninja. Kouichi has also confessed his love to Raimei, though she has not yet given him an answer. He is voiced by Satoshi Hino in Japanese and Chris Burnett in English.

Source: Wikipedia