It's their last summer vacation together... After summer vacation starts, Hiroki and Kasumi became even closer and quickly escalate to the point where Hiroki is now vigorously training Kasumi in anal sex. During their vacation they have sex over and over and learn how enjoyable it can be.In compassion, Miya is busy with going to cram school and being tutored for her college entrance exams, so she can't see Hiroki very much. Also, because she's rapidly becoming a more mature woman, she keeps getting hit on by guys in public... All three of them started thinking about how they want to live their lives as they start to become independent adults... As each of them chooses a new life path, they also realize that the time they have together now is limited and have sex with one another over and over while trying to understand their reason for existing.