The Best Relationship

Nanase (♂), who is aiming to go to art school, brought his girlfriend to his apartment today as well. Just then, Miyu, who is 4 years younger, arrives. Miyu thinks of Nanase like an older sister because her painter father had her Nanase dress up as a woman until she entered junior high school. She hasn't seen her in a long time, so Nanase is nervous about her younger sister, who is now in high school. She takes a bath with her, sleeps with her on the same futon, and Miyu is the same as before...