Haruna Aizawa thinks that school life is just like a monkey mountain--all the monkeys form cliques, get into fights, and get back together again. The school that she just transferred to is no exception. There's even a boy called Macharu Yamashita who reminds her of a baby monkey!

Talk of a future engagement between Haruna and her father's right-hand man puts a damper on Haruna and Macharu's relationship. Macharu fights back in a way only he knows how--by having Haruna live with him! Will monkey love conquer all?