Occasional fan service to highlight the awkward stage of male adolescence: Mildly over-sexualised female characters, including two aged 15 and 16.
The female protagonists are often seen in somewhat provocative poses, such as bending over or casually leaning against or sitting on transparent objects. This typically causes the male protagonist to become mildly aroused and to express embarrassment.
A surreal dream-like sequence features a nude 13-year-old girl. Her butt is visible; her crotch area is vaguely visible (no explicit detail); her chest is visible (no nipples drawn). She is observed by a crowd of other characters that includes her father.
In one scene, a 15-year-old girl is taking a shower; her butt and breasts are partially visible (no explicit detail). In another scene in a locker room, the girl is taking a bath. A 16-year-old girl enters. The bather sits up and eventually stands up; her butt is briefly visible in close-up. She tries to take off the other girl's top; the sides of her breasts are visible (no nipples drawn). The situation is implicitly but not explicitly sexual.
It is implied that the 13-year-old male protagonist sees the 15- and 16-year-old female protagonists in their underwear.