Season 1

A group of archaeologists open a tomb that awakens horrible monsters, while journeyman Yusuke Godai is compelled to access a strange belt from the tomb to fight back against them.

A drunkard witnessed a murder by an Unidentified Lifeform near a Church. Meanwhile, Yusuke is bothered by the idea of fighting and is unsure if it was right until he saw the daughter of one of the slain archeologists crying.

Yusuke Godai leaves the message, "I've returned to Tokyo because of some important business. But I will return tonight."

As #5 continues to rampage with her speed through Tokyo, Ichijou must come to a decision regarding whether to work alongside Yusuke.

Through his combination with Detective Ichijo, Yusuke Godai a.k.a. Kuuga is victorious over the Unidentified Lifeform #5, Zu-Mebio-Da.

In the battle against Unidentified Lifeform #6, Zu-Batsu-Ba, who had been appearing frequently in the Suginami ward, Kuuga's body changed from red to blue...

Three months have passed since the series of events with the Unidentified Lifeforms broke out.

During the battle with the bee-type monster Me-Badjisu-Ba that approaches from the sky, Kuuga's body changes from blue to green.

At the combined investigation headquarters of Ichijo and other detectives, they've confirmed from their investigation so far that the Unidentified Lifeforms have a habit of gathering in one location...

As Yusuke tries to convince Minori to accept his changes, he tries to figure out a method to bring out the fourth Kuuga form.

Yusuke's plan to meet with a former teacher to keep an old promise becomes interrupted with the attack of a powerful Gurongi.

Through the efforts of Kuuga and the police, Unidentified Lifeform #46 Go-Gadoru-Ba is defeated. However it simultaneously means #0 will bring forth the ultimate darkness.

Yusuke resolves to become the 'dreadful warrior' in order to defeat #0, and before that final deciding battle, he rides his bike through the unrelenting downpour to give thanks once again to all the people who supported him.

To defeat the one who brings the ultimate darkness, N-Daguba-Zeba, Yusuke transforms into the Ultimate Form, the dreadful warrior. Staining the brilliant white snow field with crimson blood in this literal fight to the death, at last, the conclusion is reached....