今日からお前の妻は俺のモノ ～入れ替わって他人妻にヤリたい放題～

Kazuma Hasebe is going nowhere fast, working multiple jobs just to make ends meet. After a bad day of gambling, he's skulking around town when he runs into Nao, the "hot girl" from back when he was still in school. She doesn't remember him. Actually, she's visibly disgusted at the sight of him, and when Nao's fiancé Takauji shows up he piles on the abuse as well. The whole traumatic experience transforms Kazuma into a stalker.

One day, while peeking into Nao's apartment, he gets into a tussle with Takauji and they take a fall down a flight of stairs. Nao hears the commotion and runs out to fuss over Takauji... but something is different.