After her politician father is disgraced in scandal, Haruna Aizawa transfers to a new school. Haruna is convinced that school life is just like a monkey mountain—all the monkeys form cliques, get into fights, and get back together again. She even meets a boy named Masaru (aka Macharu) who reminds her of a baby monkey! (Source: Viz)

Includes a side-story about Masaru s younger sister in volume two. There is also a side-story in Volume 5 about Atsu and Macharu s meeting in third grade.