俺のねーちゃんと転校生がエロくなった理由

True love and school life simulation with an immoral dilemma.
Freely enjoy the time between Golden Week holiday and Summer Vacation.

Daily life was peaceful but busy:
You were deeply involved in school, and were dating a transfer student.
Then you had that sweet, dangerous night with your sister.

The secret thrill led to another incident. And another. Each day the perversion escalated a bit more.