Seigi 0-ten no Kanojo

In a world where the birthrate is declining and the population is aging, a new school subject called “sexual skills” was adopted. Hikawa, who has excellent grades in everything else, is unable to raise her grades in the “sex skills” subject. So she asks her childhood friend Shiba to help tutor her in the subject.
When a girl with little sexual knowledge comes into contact with the real pleasures of sex...
(Source: Melonbooks, translated)
Note: Released at COMITIA148.