Adolescent girls start to worry about the gazes of boys and men around them, and become interested in the differences between their bodies and men's bodies, and the differences in genitals. The lively girls, with dazzling tan lines from their school swimsuits, awaken to sex, experience becoming adults over the summer vacation, and grow up. A secret record of sex between Mikako, Maiko, and Hoshizora, kept secret from their parents.