Risa is a precocious elementary school student who finds her classmates boring and childish. As a result, she spends the majority of her days isolating herself from them. However, there is one person she looks forward to seeing: Megumi, the high school student next door. Risa looks up to Megumi, finding her kind, intelligent, and even attractive.

When Risa's mother goes away on a business trip, Megumi asks Risa to stay over. Naturally, Risa is both excited and nervous at the prospect of living with her older best friend. But little does she know, Megumi's intentions are far from innocent.