Yamane Saki is one of Ryuuichi's and Ushimaru's classmates. She's among the school's more excitable teenagers.
Saki has shoulder length hair that's colored in a darker shade in the anime.
Saki is enamored with several boys that attend her school, and isn't as shy about admitting it as some of her friends. She is one of many girls in her class who admire Ryuuichi and Hayato, both for their good looks and kind natures. She springs up when she recalls how Ryuuichi picked up and returned her eraser when she dropped it. And despite Hayato's attractively cold demeanor, she can tell he's nice since he joined the babysitter club to help Ryuuichi out. Saki also harbors crushes on Yagi and Nezu from the advanced class.