Kenta Usui has had a ruff life. His father ran out on his mother and him when he was small and his mother is always picked on at her works to the point that she gets fired easily.He also has a very scary face that most don't want to go near him. He just moved into a new town and started going to a different school when he meets a strange girl that keeps running from him. That wouldn't be so different exsept that he finds shes a vampire! After learning this secret, he becomes her watcher in the day time for fear of losing all of his memories. It becomes even more troublesome when he falls in love with her.
[Edit]Kenta Usui (雨水 健太 Usui Kenta) is the first person to have found out Karin's secret. Under Anju's suggestion, the Marker family made him an ally to aid in caring for Karin during the daylight hours.
Kenta and his mother live in a one room apartment and do not have much money. Consequently Kenta can't afford three meals a day, which means he's often hungry during the middle of the day. Karin, realizing this, begins making him a bento every day. Kenta works with Karin part-time at Julian restaurant, and gets all the hours he can to support himself and his mother. He dreams of being a model citizen with a family and a good job.
As a child, he was ignored by his maternal grandmother due to the circumstances of his birth, leading to his being a person who tries to live a life free of prejudice and being able to sympathize with Karin's unusual nature. He offers his neck to Karin to bite whenever she needs so she won't have any more nosebleeds. Karin ends up biting him twice, the second following their first kiss. When she is kidnapped, Usui aids the Markers in tracking her down, led by Sophia Pistis, the spirit of the first Psyche. While they are there in Kenta's home town and at Karin's suggestion, Kenta goes to see his sick grandmother, not wanting to lose the last chance to reconcile with her. After Karin's memories are modified by her family, Kenta, whose memories couldn't be erased, promises to keep her heritage a secret and to make her happy. At the end of the series, they are married with a child, the reincarnated spirit of Sophia.
In the anime television series, Kenta Usui is voiced by Katsuyuki Konishi in Japanese and Yahav Rom in English.