Yotsuba Sugimoto is the protagonist of a PFP game and goes by the nickname "Yokkyun." Her character design deliberately parodies the art style of the classic visual novel Kanon.
What makes her stand out is that she's the only character from an actual game who appears repeatedly throughout the series. Keima considers her the "ideal heroine"—and he's genuinely obsessed with her. Whenever someone insults or mocks her, he either spirals into depression or explodes in anger. Fans often note that his attachment to her is pretty extreme, even by his standards.
Content compiled by AnimeList.moe from publicly available sources.
