Yūji Moritaka is a Japanese manga writer best known as the original creator of the long-running baseball series Gurazeni. He is credited as the writer for the series, with various artists providing the illustrations. His birth year is 1963, and he was born in Nagano Prefecture, Japan. Moritaka is established as a creator within the seinen manga genre, which targets young adult and adult male audiences.

Moritaka's primary notable work is Gurazeni, a manga series that focuses on the professional baseball world through the lens of player salaries and statistics. The original Gurazeni manga was serialized in Kodansha's Morning magazine from December 2010 to August 2014. This series was followed by several sequels and spin-offs also written by Moritaka, including Gurazeni: Tokyo Dome-hen (2014-2018), Gurazeni: Pa League-hen (2018-2021), and Gurazeni: Dai League-hen (2021-present). The series has also expanded into spin-off works such as Gurazeni: Natsunosuke no Seishun (2020-2022) and Shōwa no Gurazeni (2021-present), a spin-off illustrated by Kawa that depicts professional baseball during the Shōwa era.

The Gurazeni franchise has been adapted into other media. A 24-episode anime television series adaptation produced by Studio Deen was broadcast in 2018. Moritaka is credited as the original creator for this anime adaptation, which covers the first two seasons of the show. The series was directed by Ayumu Watanabe, with Hideo Takayashiki handling the series composition.

A recurring artistic identity in Moritaka's work is a realistic and analytical exploration of professional baseball, emphasizing the business and statistical aspects of the sport over the typical themes of youthful rivalry or superhuman feats. The series follows Natsunosuke Bonda, a relief pitcher whose career is driven by his obsessive focus on player salaries and performance data. The title Gurazeni itself is derived from a famous phrase by legendary Japanese baseball coach Kazuto Tsuruoka, meaning "there is money to be made on the field". Moritaka has incorporated real-world elements into his fictional narrative, with later installments featuring a team, the Sendai Golden Cups, that is closely modeled on the actual Tohoku Rakuten Golden Eagles of Japan's Pacific League. He has stated that he conducted research for the series by collaborating with the team and visiting their facilities.