Once upon a time, this world was created and destroyed by a single girl. The ones who saved the girl's heart were Hyper Agent Gridman, who appeared from another dimension, a monster with a heart created by the girl, and high school student Yuta Hibiki. Yuta, who has advanced to the second year of high school, decides to confess to Rikka, who is in a different class. However, their peaceful daily lives are shattered by the sudden appearance of a monster. Gridman reappears in front of Yuta
