The final instalment in the popular series featuring the duo of Hama-chan, a lifelong low-ranking employee and fishing enthusiast, and Suu-san, the chairman of the company where he works.

High school student Kyosuke Shikijo is the most talented member of the school's martial arts of the fist club. His late father was detective and Kyosuke share his father's strong sense of justice. Kyosuke also has a secret. Kyosuke likes to wear female underwear and transforms himself into the alter ego "Hentai Kamen," wearing female underwear and gaining superhuman powers. This unusual interest also comes from his parents, with his father a masochist and his mother a sadist. By chance, Kyosuke gets the underwear of female high school student Aiko Himeno. With her underwear, he gains various pervert techniques and attempts to protect Aiko from a dirty and heinous teacher.

Starting in 1970s Hokkaido, the film charts the moral descent of Detective Moroboshi over three decades, the young cop quickly gets a bit too cozy with the other side of the law when his senior colleague Murai teaches him the ropes and ruts of the police business. Soon, he swaggers and rants through the streets of Sapporo a lean, mean, sex‐crazy bully, indistinguishable from a yakuza.

Reiji Kikukawa, who has a strong sense of justice, graduated from the police academy with the lowest score ever. He becomes a police constable, but is suddenly fired by the Police Chief due to "disciplinary" issues. In actuality, the firing is part of a carefully orchestrated plan to set him up as an undercover cop in the Yakuza.

News about the disappearance of panties is still being covered every day. Kyosuke still wears Aiko Completo's panties to battle evil. Meanwhile, Aiko has mixed emotions and decides to get her panties back. Kyosuke suffers from the loss of Aiko's panties and disappears, but his biggest enemy yet is about to materialise.

Ayaka Ichijo is a graduate student with an IQ of 200 who tries to investigate the strange deaths happening nationwide after people supposedly watched a cursed video and her younger sister also did the same out of curiosity.

Ono Yasuomi is a cram school teacher with poor communication skills. He hopes to get married but doesn't know what ordinary means and feels awkward on dates with women. He asks Kasumi, a student who knows lots of trivia about romance, to teach him the meaning of ordinary.

Hama-chan and his wife are ecstatic about their long-awaited pregnancy. Meanwhile, Su-san's nephew joins Hama-chan's department at the company.

Yumiko returns to work in Hama-chan's department. She had once left the company after getting married, but a dark shadow now seems to loom over her.

Three male gangsters are forced by their boss into becoming a trio of female pop singers.

Dan Mitsu stars as Kana, a female employee at a publishing company who strikes up a sexual relationship with a younger co-worker. He soon discovers that Kana's fetishes extend to sadomasochistic tendencies, involving a mysterious man only known as "Sensei". This discovery will push his relationship with Kana to a new, dangerous level that he may not be ready for.

Ueda employes Yamada to go a mysterious island in search of a girl (played by Maki Horikita) that disappeared 10 years ago. They discover the island is run by Kobako Sachiko, who can appear and disappear via boxes, among other strange powers.