Recap of leading up to the seventh season.

Segua Kingdom has been losing the war against Ninterdo Empire but the tables are turned by the appearance of a boy called Gear. All the characters are parodies of Nintendo or Sega games such as Sonic the Hedgehog, Super Mario Bros., The Legend of Zelda etc.

Long ago, the gate to the world of darkness was sealed. Now evil warriors, known as Remnants, are trying to reopen the gate and let demons take over the world. However, at Tobira High School, there exist guardians of the gate who must risk their lives to prevent the gate from being opened.

Based on the one-shot manga .