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. He often like Takeru 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.