USA, 1949... Kevin Yamagata, an American of Japanese descent, is the creator of the comic bestseller "Billy Bat." The main character is a bat - the comic is a mix of classic Disney and superhero styles. Suddenly, Kevin learns that the bat character has supposedly existed in Japan for a long time. Did he not actually create "Billy Bat" himself? Kevin decides to travel to Japan to find out more and to apologize to the character's creator for the idea theft. As soon as he arrives, he gets caught up in a whirlwind of dramatic events that will turn his life upside down...