Tsugumi Ohba (大場つぐみ Ōba Tsugumi) is the author/mangaka of the manga series, Death Note. It is widely speculated that this is a pen name. As mentioned in the Death Note panels, he/she was born in Tokyo, has a hobby of collecting teacups, and develops manga plots day and night on a chair while holding his knees in a way reminiscent of a character in Death Note, L. Death Note ) is a Japanese series originally written by Tsugumi Ohba and illustrated by Takeshi Obata centering around a young high schooler who decides to rid the world of evil with the help of supernatural sources. ...

Based on the information page on deathgod.org [1], it is strongly believed that Tsugumi Ohba is actually Hiroshi Gamou, author of the JUMP series Tottemo! Luckyman. It is speculated that he chose to hide his identity due to the fact that the Death Note series is very different from his past work. Gamou was born on August 17, 1962 in Tokyo Japan and has blood type B. Some of Gamou's previous assistants included Murata Yuichiro (Eyeshield 21) & Nishi Yoshiyuki (Muhyo & Rosie).