You don't even know that.

[ Akutagawa seems surprised. Manga seems to be all the rage with the youth, it's rare to hear that no one has heard of it.]

Calling it a picture book or even a comic book isn't exactly it. Manga is best described as a visual novel, the pictures and dialogue carry the story along. There are different genres so anyone can find something that speaks to them. Though I will warn you to read the book in the right direction, otherwise you might be confused.