Tatakae! Osper

After the catastrophe that destroyed their continent, the inhabitants of Mu have adapted to living in the ocean, in cities covered by huge domes. Many years later, the inhabitants become psychic.

During an annual battle held to determine who is the best Mu psychic, Osper, a boy with a strong sense of justice, battles Drome, an older, brutish boy who is vengeful and evil. Osper wins the battle and after being defeated, Drome destroys the dome in revenge and escapes to Earth. Osper is sent to chase Drome and avenge his people. Above ground, Osper meets Yumi Kaizu, the daughter of the head of a police special forces unit, the International Crusader Police (国際十字警察, Kokusai Jūji Keisatsu). With the collaboration of Kaizu, who brought Osper into her unit, Osper follows the tracks of Drome to locate him.

Strange incidents occur on Earth, but on a scale never seen before. As it is revealed that Drome was the one who was involved in all of these incidents, Osper fights him and solves each cases, whereas Drome flees every time.

After being cornered, Drome activates the ultimate weapon to destroy the Earth, and engages Osper on the place be prepared for a final battle. After a fierce battle, Osper is victorious and Drome admits defeat to him by saying, "All the bad things I've done so far are due to the fact that I was not able to defeat you and win". In his final hours, he notifies Osper of the location of the ultimate weapon. Osper immediately stops the ultimate weapon from operating, which allows both Drome and Osper to return to their home world under the sea. Chief Kaizu, who learned of Osper's return, reads a letter left by Osper for Yumi, which states "The next time I meet you, I want to be a ordinary person".

Osper (オスパー, Osupā)

Voiced by: Keiko Yamamoto

A Mu psychic. He comes from the undersea world in pursuit of Drome. He become a member of International Crusader Police at the recommendation of Yumi and used five types of supernatural powers to fight against Drome and the evil of the Earth. He specializes in teleportation.

Drome (ドロメ, Dorome)

Voiced by: Ryo Abe

An ambitious and brutish psychic who rivals Osper. He destroyed and fled from the dome of Mu in revenge for losing the battle against Osper, and joins the evil of the Earth. He specializes in telekinesis.

Yumi Kaizu (海津 ユミ, Kaizu Yumi)

Voiced by: Megumi Tama

She met Osper while he was on Earth's surface and invited him to the International Crusader Police, led by her father, Chief Kaizu.

Chief Kaizu (海津 長官, Kaizu Chōkan)

Voiced by: Iemasa Kayumi

Yumi's father who is the head of International Crusader Police.

Robert (ロバート, Robāto)

Voiced by: Akira Okuhara

A member of the International Crusader Police.