The player takes on the role of a female protagonist, Mana, who is visiting a rich friend's house for the summer.
However, there are a few problems: first of all, her little sister, Kurumi, comes along and she doesn't get along with the rich friend, Kyouka; secondly, both Kurumi and Kyouka are batshit insane and more than willing to Murder the Hypotenuse.
This game contains the following tropes:
- A-Cup Angst: Kyouka
- Axe-Crazy: Kyouka
- Sister Sister Incest: A non-explicit version Mana (the main character) and Kurumi.
- Multiple Endings: Several. A lot of them end up in death by Yandere.
- Ojou: Kyouka
- Onee-sama: Kurumi
- Psychotic Love Triangle: Kurumi, a yandere, likes Mana (also her older sister) and Kyouka, another yandere, likes Mana.
- Red Eyes, Take Warning: Kyouka, the Axe-Crazy love interest.
- Slasher Smile: Multiple times from both Kurumi and Kyouka.
- Yandere: Kurumi and Kyouka.
- Yuri Genre