Many of the scenes and themes are sexual and suggestive throughout the anime, but no intercourse or explicit nudity is ever shown.
Throughout the series, many characters have to face their "inner selves" called Shadows. These Shadows represent the character's repressed emotions and feelings, some of which are sexual.
Yukiko's shadow flirts with viewers of the Midnight Channel, claiming that her "lacy unmentionables are ready to go, just like her heart". Her shadow also says that it "wants to score a hot stud".
Kanji's shadow makes several homoerotic passes at the main male heroes (for humorous reactions, they aren't attracted whatsoever). His shadow acts in the stereotyped "gay" fashion and runs around wearing only a bath towel. During the fight against it, Kanji's shadow has two muscle-bound henchmen that make homosexual passes at the male heroes again and lightly gropes their butts (the scene isn't meant to be erotic, just played for laughs at the humiliation of the males).
Rise's shadow is the most sexual, wearing a skimpy bikini and claiming that she'll bare her naked body to everyone watching the Midnight Channel (she never does). The camera zooms in on her cleavage and bottom a few times as she taunts the heroes. When they go to find her, they discover she is hiding out in a strip club. Nothing is shown as the club is empty aside for monsters, but later on Rise's shadow proceeds to pole dance. The scene only lasts a few seconds.
The character Teddie is a wannabe ladies man. He frequently flirts with girls and older women for comical reasons. In an episode, he appears completely nude in a bear suit, covered from the waist-down.
Kanji is introduced as a homosexual and frequently teased about being gay a few times during the series, although after his shadow is defeated, he claims to be straight. In one scene, an overweight girl rolls over onto him, shoving his face into her cleavage, making him blush. The next morning, the same girl "breaks up with him", claiming that the previous night never happened (the scene is comedic in nature).
On a field trip, a class of high-schoolers spends the night in a hotel. They later learn that it's actually a love hotel (a Japanese hotel used mainly to have sex in). The girls and boys stay in separate rooms, but inside the beds rotate and play romantic music for laughs.
A nurse tries to seduce Yu, who dismisses her advances.
In one episode, the characters go to relax and bathe in hot springs. The boys (only wearing towels) accidentally come in on the bathing girls, who are also naked (but their bodies are shown from the neck up). The girls then proceed to throw buckets at them, yelling to get out. In a later scene, the boys ask each other if they "saw anything".
A group of boys sneak into a girl's hotel room at night, trying to raid through their belongings and peek on them. One character comically sniffs a girl's toothbrush.
One of the females with large breasts is jokingly referred to as "melons" and "funbags".
In the infamous King's Game scene, the heroes (who are underaged teenagers) become drunk (see Alcohol/Drugs/Smoking). They proceed to play a "truth or dare" type game and one of the girls has to sit on a boy's lap. One girl lays her head on his lap while another discusses other embarrassing dares.
Nanako, a seven-year old girl, says that a lady called her brother a "manwhore". Later, she innocently asks if the boys are "horny", not knowing what it means.