Wissenswertes

His daughter, Mari Hirai, is a quite popular comic-artist.

He wrote one time that the characters he creates are strangely linked to Japanese gods. Eitoman when word Eito (eight) is translated into Japanese becomes Hachi which then makes Eitoman into Hachiman-sama a famous Japanese god, and character Inugami Akira (of his Wolf Guy Series) when the kanji character of Inu is slightly modified becomes the character Dai, and Akira can be read as word Myo, so the name becomes an anagram for Daimyojin - another famous Japanese god. He claims this happened quite by accident, but he's not sure because sometimes a god claiming to be Hachiman stands by his bedside when he's sleeping.