The story begins in 1949 Los Angeles. Kevin Yamagata, a Japanese American cartoonist, has built his career on Billy Bat, a sharp, wisecracking detective beloved by readers. But everything shifts when Kevin realizes he may have unknowingly copied the character from an image he once saw in Japan.

Determined to find the truth, Kevin returns to a devastated, postwar Japan. What he uncovers goes far beyond questions of inspiration or theft. The image of the bat is ancient, surfacing again and again across history, tied to moments of upheaval, power, and violence.