The Absolute Evil for My Hero

A hero novel about adolescence, painting justice and evil.
Some province, some region somewhere in Japan, Tsukimori City. Structured the same as any other city, Tsukimori has just one point that sets it apart from the rest. That is the fact the city is protected by a single hero.
A young girl who usually lives her life as a high school student, Mia. Whenever the kaijin of the evil organization Calamity Co. Leviathan threaten the peace of the city, she transforms into a hero and fights day and night. A young boy, her childhood friend Takeru watches over her work as a hero. A normal high school student with no redeeming features, Takeru had a certain secret—that he himself was the leader of Calamity Co. Leviathan, Lord Helvenom. Takeru’s goal, it is all for Mia, fated to live as Gaimoon, forced to battle evil for the rest of her life, to continue standing as her sworn foe.
What sort of fate awaits the relationship of evil leader and hero?
To protect those they hold dear, the battle wages between beloved. This is a hero novel of justice and evil!