真面目な女子大生みこは、隣に住むだらしなお姉さんの似鳥に毎日悩まされており、朝会えば二日酔いで酒臭く、夜になるとオナニーでデカい喘ぎ声をあげて勉強を妨害して来る似鳥を反面教師として見ていた。しかし、ついに我慢の限界を迎えたみこは似鳥に注意をしに行く。そして、それがきっかけでみこの価値観はぶち壊され、性癖は大きく捻じ曲げられてしまうことになる…。

Miko, a serious college student, is tormented daily by her slovenly neighbor, Nitori. Every morning, Nitori smells of alcohol from a hangover, and at night, she masturbates, making loud moans that disrupt her studies. Miko sees Nitori as a negative example. However, she finally reaches her breaking point and goes to confront Nitori. This incident shatters Miko's values and drastically alters her sexual preferences…