Satou Ichirou once called himself 'Maryuuin Kouga' and behaved as if he were a hero in a fantasy world. His strange behavior caused his classmates to bully him and he left the school. At his new school, he tries to behave like a normal boy, but one day he meets a girl who cosplays with a blue cape. She calls herself "a researcher traveling from the outer world to search for the 'Dragon Terminal'". At first, Ichirou rejects the girl, Satou Ryouko, because her behavior reminds him of his embarrassing past, but he changes his mind after seeing her getting bullied. In order to bring Ryouko back to real life, Ichirou accepts her and his past and begins the final battle as Maryuuin Kouga.

Yuta Togashi has a problem. He used to be a "chunibyo," one of the thousands of Japanese students so desperate to stand out that they've literally convinced themselves that they have secret knowledge and hidden powers. But now that he's starting high school, he's determined to put aside his delusions and face life head on. The trouble is Rikka Takanashi, his upstairs neighbor, is just a little bit delusional herself. And she knows all about his past indiscretions.