17.3 about a sex

Sakura grows nervous when her boyfriend invites her to his house. Having no experience with sex, she turns to her friends to help her prepare.

Tsumugi gets invited to the movies by a male childhood friend she hasn’t seen since junior high. At the end of the night, she comes to a realization.

Yuna excitedly tells Sakura and Tsumugi about her new 26-year-old boyfriend, but when her stomach begins to hurt, they fear that she is pregnant.

Sakura hears odd sounds coming from her mom's room. She tells her friends about it but is shocked when Yuna suggests her mom is using a vibrator.

Feeling confused about Yu's sexual orientation, Sakura consults Tsumugi and Yuna. Later, she blames herself when rumors about him spread at school.

When Yuna fears her boyfriend is cheating on her with a larger-chested girl, she follows him and is horrified to see him entering a brothel.