Tsugumi Ohba is the pen name of a Japanese manga writer whose real identity is a closely guarded secret. Born in Tokyo, Ohba came to prominence through a celebrated creative partnership with illustrator Takeshi Obata. Their collaboration began in 2003 with the series Death Note, which was serialized in Weekly Shōnen Jump until 2006 and became a global phenomenon with over 30 million collected volumes in circulation. This success established a pattern of the duo working together on major projects, followed by Bakuman, serialized from 2008 to 2012, which achieved 15 million copies in circulation, and Platinum End, which ran in the monthly magazine Jump SQ from November 2015 to January 2021. Beyond these three long-running series, Ohba collaborated with artist Robico on the one-shot Skip! Yamada-kun in 2014.

The creator is credited as the original story author for various adaptations of these works. For Death Note, this includes the anime special Death Note Relight 2 L's Successors, which adapts and recontextualizes events from the latter part of the original story. Platinum End also received an anime adaptation, and Bakuman was adapted into both an anime series and live-action film, reflecting the commercial success and broad appeal of Ohba's narratives across different media.

The mystery surrounding Ohba's identity is a defining aspect of their public profile. The author has stated in interviews a preference for maintaining privacy, noting they never initially intended to become a manga creator and expected the Death Note pilot to be rejected. In these rare interviews, Ohba has cited filmmakers Akira Kurosawa and Charlie Chaplin as influences, described a fondness for collecting teacups, and mentioned developing manga plots while sitting with knees held to the chest, a habit shared with the character L from Death Note. There is persistent industry speculation that Tsugumi Ohba is a pseudonym for the veteran manga artist Hiroshi Gamo, creator of the gag manga Luckyman, with fans pointing to numerous visual and textual clues embedded within Bakuman and other works. The then-deputy editor-in-chief of Weekly Shōnen Jump declined to confirm or deny this theory, and the creator's true identity remains unverified by official sources. The thematic concerns of Ohba's work frequently explore intricate systems of rules, the nature of justice, the burden of exceptional ability, and the intense creative process behind manga production itself, as exemplified in the industry-focused narrative of Bakuman.