Most of the film deals with war, love, and intense depression.
Two teenage boys often discuss dating and girls, but innocently and never crudely. Also, in many voiceovers, one of the male characters sexpresses his feelings for a girl in the film, but not in an explicitly sexual way. he only mentions how he likes to have her around and how he thinks he loves her.
There are many instances in the plot involving love and special feelings towards others, between young adults.
An older man is obviously hitting on a younger adult woman, but just by speaking subversively with no innuendo.
A girl is shown lying in a bed, asleep, several times throughout the film (as it's important to the plot). It's implied that she has no clothes on, but we see only a bit of her cleavage and no explicit nudity.
We see a teenage girl in her bra and panties quickly as she changes, but we don't see any nudity.