Shizumu Watanabe is a Japanese manga artist born on July 21 in Ehime Prefecture. He graduated from the Osaka Communication Arts College and worked as an assistant to manga artist Akiko Higashimura. Watanabe began his professional career under the pen name Shizumu Saitama before switching to his current name. He entered the industry by placing as a finalist in the Weekly Shonen Magazine漫画漫画奖 in 2003 for the work Closet Child, followed by another nomination in 2004 for Gakusha Overdrive.

Watanabe has created several serialized manga, often working with original story collaborators. His early works include the short series Irokoi and the serial CHIMES, both published in Magazine SPECIAL. He subsequently authored Virtual Girlfriend in Weekly Shonen Magazine and Iron Maiden of Spring in Young Gangan. Watanabe achieved significant commercial success with REAL ACCOUNT, which was based on an original story by Okori. The series ran in multiple magazines, including Bessatsu Shonen Magazine and Weekly Shonen Magazine, and was compiled into 24 volumes. He later created Spell for a Witch, which was published in Weekly Shonen Magazine across four volumes in 2020 and 2021.

Watanabe is the sole creator of the manga Dead Account, which he writes and illustrates. The series began serialization in Kodansha’s Weekly Shonen Magazine on January 18, 2023, and later moved to the Magazine Pocket website on October 7, 2023. As of early 2026, the series has been compiled into multiple tankobon volumes. An anime adaptation of Dead Account is produced by animation studio SynergySP, with direction by Keiya Saitou and series composition by Mitsutaka Hirota. The anime premiered in January 2026, airing on TV Asahi and streaming on platforms such as Crunchyroll. The story follows Soji Enishiro, a provocative streamer who awakens cyberkinesis and is recruited to attend a school that trains spirit mediums to combat digitized hauntings and ghost accounts.

Watanabe’s artistic identity often blends contemporary digital culture with supernatural action. His works regularly feature themes of online identity, social media, and modern technology intersecting with traditional ghost stories and spiritual concepts. His professional experience includes providing end card illustrations for the anime series The Comic Artist and His Assistants and The Heroic Legend of Arslan. Watanabe has also been involved in volunteer efforts following the 2011 Tohoku disaster and contributed to the Pray For Japan charity fanzine. His significance in the industry lies in his consistent output of commercially viable supernatural thrillers for the shonen demographic, with Dead Account representing his latest major work to receive an anime adaptation.