Adult PC Game: Ane Tsumami ~Miwaku no Osananajimi Onee-san Hitozuma to no Mecha Ero Dousei LoveLife~ by ANIM Archive

In order to go to cram school, the main character, Kinugawa Haruka, will be staying at his aunt's house for a while.
When he got used to his freeloading life, it was decided that his uncle would be sent away from home, and he would be alone with his favorite aunt, Shion.
On top of that, when he was young, he was on good terms with an older sister, Rena, who he admired, and now he lives with her...his aunt and her friend, whom he admired like an older sister.
The flirtatious cohabitation activity begins!