Yami to Bōshi to Hon no Tabibito (ヤミと帽子と本の旅人, Yami to Bōshi to Hon no Tabibito? possibly translated as Yami, the Hat, and the Travelers of the Books), also known as Yamibō/Yamibou for short, is both a Japanese adult visual novel published in late 2002 by Root, and a non-adult, thirteen episode anime series released by Root and Studio Deen in 2003. Although the characters and their relationships remain basically the same in the game and anime, the storyline is quite different.

Source: Wikipedia