Tsundere Inran Shoujo Sukumi  

Złośliwa i sucza Sukumi, ツンデレ淫乱少女すくみ

During his summer break at school, the protagonist stumbles upon Sukumi, a classmate, engaging in self-pleasure in the female locker room. "If you don't want me to make this public, come see me every day!" Her demands become increasingly bold, and they eventually have sex in the pool. This marks the beginning of an erotic summer holiday with Sukumi for the protagonist.