Ken (ケン) is one of Teru Kurebayashi and Kiyoshi Hasegawa's close friends. He is known as the buck-teeth boy and is notably tall and skinny, with freckles on his face. He is in love with his friend Kako, who he begins dating after Teru and her friends take a trip to the beach for a studying session.
Ken often joins Yoshi when role-playing comedic situations and energetically follows Teru in her declarations that they will not allow themselves to be looked down upon because of wealth or intelligence. He does not seem to excel academically, and apparently resorts to cramming right before exams. His extracurricular activities include being in a light music band with Yoshi.