Plus, I'm at least curious as too why the MC is living with this girl... Are they siblings or something? Should this be tagged as incest?
I just played through the intro and this is explained as follows:
- The female character's name is Shizuku, and she is the daughter of MC's relatives (implied that she is a cousin)
- She is 8 years younger than MC
- MC is a working adult now and has been sent by his company on a temporary secondment to a different city.
- Conveniently this new city is where his relatives live so it was agreed he would stay at their house for the duration.
- The mother and father of Shizuku decide to go on an extended holiday since MC will be there to look after the house and their daughter.
- "And thus begins my story of a hot and humid summer with Shizuku."