81diver (Japanese: ハチワンダイバー, Hepburn: Hachi Wan Daibā) is a manga written by Yokusaru Shibata. It was serialized in Weekly Young Jump, published by Shueisha. It is aired as a drama series from May 3, 2008 starring Junpei Mizobata and Riisa Naka. The title refers to the main character's shogi nickname, which comes from the words of his former teacher who once told him to dive into the 9 by 9 (81) squares of the shogi board.