Based on the erotic game by Ume Soft.

Wakasa Souji is someone who is too obsessed with Ominato Natsuko, a cute girl who works in a Supermarket. Due to lacking the expertise to communicate and talk with Natsuko, Souji only paid close attention to Natsuko. Natsuko has recently been dating Shibata the handsome but Playboy man, and he plans to take Natsuko in just 1 week to kiss and sex. That's why Souji wants to save Natsuko from that goddamned man in his own way.

(Source: Nekopoi and Has Been Translated and Edited)