Chaos Queen Ryouko 4 Moriyama Yuri & Ikumi Shimai Heidon Hen

Shinichi works as a temporary lecturer in a private school. He stays at a private family keeping a glamorous, but unstable position. It's summer now and the family he stays in goes overseas. Suddenly a cute girl Yuri shows up in his life certainly aiming to marry him.

[From vndbreview]