Kengo Usui (碓 健吾 Usui Kengo) is a member of the Student Council Security Division, a 1st year student at Tenbi Academy, and one of the supporting characters of the Maken-Ki! series. He shares his perversity with his close friend Takeru Oyama, who are known around campus as creepy perverts. He is madly in love with Kodama Himegami and is aspiring to become her boyfriend through impressing her.
It is later revealed that he is a clone of Takeru Yamato, who escaped and began a new life away from Kamigami. He was originally known as Sample 0-01.
He has open feelings for Himegami and is supposedly in her fan club. Like Takeru, he loves to peeks on girls when they are in the shower, changing, etc. Much like Takeru, Kengo has a strong sense of justice. He sets Takeru straight, after seeing Inaho cry, figuring out what caused it. He calls Takeru a hypocrite for claiming to want to protect girls, yet making Inaho cry.
Point Man - Kengo has an internal type maken. His maken "Point Man" allows him to switch the places of an object he touches with that of another.
Element Negation - an ability shared only by one other clone, Kengo has the ability to completely nullify any element he comes in contact with.
Kengo’s best friend. With him, he shares many qualities, especially his habit of seeing attractive girls changing clothes or bathing.
Kengo’s Friend. Kengo is in love with her, but Himegami treats him as if he is her servant.
Kengo’s Friend. Kengo shows his love and concern for her, to the point that he hit Takeru when he made her cry. In addition, they are always worried that the person they like (Kodama and Takeru respectively) are going out with each other or with another person.
Kengo’s superior and friend.
Principal and friend. Minori left him in charge of the Academy as part of his strategy to win the appreciation of female students, but the results were disastrous.
Teacher and friend. Like Takeru, he always has fantasies that are related to Aki.
Teacher and friend.