Kengo Usui is a student of Tenbi Academy and the equally perverted friend of Takeru. He is a freshman in the Maken-Ki.
They initially meet on Takeru's second day at Tenbi, when both of them pretend to be sick and go to spy on the girls at their physical exam.
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.