Natsu e no Hakobune III

The first summer vacation after being out of town, for the first time after several months, the protagonist returns to his hometown. Even though the circumstances have changed, his summer begins like always......or it should have been. Unexpectedly, a story about his cousin's arranged marriage comes up. And as a result, the protagonist eventually realizes the hidden feelings of his cousin, his younger sister, and his childhood friend── By being deeply connected with these girls, a new kind of summer begins. Set during the summer in the countryside, with the alluring love and desire of these 3 girls intertwine, begins an immoral love story.