Momoko is a beautiful young sword fighter who was born inside a peach (momo in Japanese). She lives with her constant companions—the dog god Inugami, the monkey god Sarugami, and the pheasant god Kijigami—in a peaceful paradise. However, a demon army led by devil king invades the paradise and steals the precious treasure that protects Momoko's land. To retrieve the treasure and save the people, Momoko embarks on a great adventure with her three companions.

Second year high school student Ichirou Satou has always been an average person—that is, until he runs into some not-so-average situations with his teacher, Kana "The Demon" Kojima. Kojima is Satou's Japanese language teacher with a reputation for being so ruthless that even school delinquents bow down to her. One fateful day, things escalate when Satou runs into Kojima in the restroom, leading them to share an intimate encounter that makes his imagination run wild for days after. Nande Koko ni Sensei ga? follows the daily life of Satou and his teacher as they continue to meet under similar conditions, growing ever closer with each encounter.

Mini-OVA specials bundled with each Blu-ray/DVD volume of Kenzen Robo Daimidaler.

Battles continue between "Penguin Empire", the mysterious life form which arrived on earth all of a sudden, and "Beauty Salon Prince", the secret anti-Penguin organization. In order to fight Penguin Empire's gigantic "Penguin Robot", Beauty Salon Prince has developed their ultimate weapon, "Daimidaler", and is now looking for the pilot. They choose Koichi Madanbashi, a hot-blooded high school boy who is mad about big boobs, because he is the factor of "Hi-ERo particles", the source of unknown energy.