Based on the erotic game by POISON.

While recuperating from an injury sustained at work, the protagonist Shougo is astonished to see a young wife move in next door to his apartment. She - Minami - was his senior in school and a notorious delinquent. However, her looks, which were already outstanding back then, have only become more sexy, and Shougo, who has always wanted to embrace her despite being his underling, cannot stop having sexual fantasies. So he comes up with a plan to exploit Minami's weakness, who does not want her husband to know about her past misdeeds!!

(Source: Parabook, translated)