Masaki Okayu is a Japanese author and manga creator best known as the original creator of the Bludgeoning Angel Dokuro-chan franchise. Born on January 27, 1979, in Saitama Prefecture, Japan, Okayu began his professional career as a writer in the early 2000s. He is primarily recognized for creating the light novel series Bokusatsu Tenshi Dokuro-chan, also known as Bludgeoning Angel Dokuro-chan, which debuted in June 2003. The series was first serialized in Dengeki hp magazine, published by MediaWorks (later ASCII Media Works), and the light novels were illustrated by Torishimo. The original light novel series ran until October 2007, spanning eleven volumes.

The success of the light novels led to multiple adaptations across different media. A manga adaptation of Bludgeoning Angel Dokuro-chan was created by Mitsuna Ouse (also credited as Mitsuna Sakuse) and serialized in Dengeki Comic Gao! from August 2004 to June 2006, compiled into three volumes. The story was later adapted into an original video animation anime series directed by Tsutomu Mizushima and produced by Hal Film Maker. The first anime series aired between March and September 2005, comprising eight episodes, while a second series, Bokusatsu Tenshi Dokuro-chan Second, was released between August and November 2007 with four episodes. The anime adaptations retained the core premise of Okayu's original story: a teenage boy named Sakura Kusakabe who is destined to create a controversial technology in the future, leading to a angel assassin named Dokuro being sent from the future to kill him, though she ultimately chooses to protect him instead, often killing him accidentally or impulsively before resurrecting him with her magical spiked club.

Beyond the Dokuro-chan franchise, Okayu has continued working as a light novel author and manga writer. His bibliography includes light novel series such as Ore ga Doutei wo Sutetara Shinu Ken ni Tsuite, which began in 2016, as well as other titles published under the Dengeki Bunko imprint. He also wrote the manga Moriguchi Orito no Teiougaku, a comedy and romance series illustrated by Rin Sanada that ran for two volumes. Additional light novel credits include works from 2008 through 2021, indicating sustained activity in the industry.

Okayu's creative identity is strongly associated with dark comedy and absurdist humor that blends extreme violence with whimsical, lighthearted elements. Bludgeoning Angel Dokuro-chan exemplifies this approach, combining graphic and repeated depictions of violence with magical girl tropes, slapstick comedy, and ecchi fanservice. The series is noted for its parody of the magical girl genre, subverting expectations through its protagonist who both protects and repeatedly kills the male lead. Recurring themes in Okayu's work include supernatural interventions in everyday life, romantic misunderstandings, and exaggerated comedic violence that serves as a narrative device rather than genuine horror. His industry significance stems primarily from creating a franchise that achieved success across light novels, manga, and anime formats, with the Dokuro-chan series gaining a cult following and receiving an English-language license from Media Blasters for North American release. A PlayStation 2 visual novel game titled Game ni Natta yo! Dokuro-chan: Kenkō Shindan Daisakusen was also released in Japan in November 2005, further expanding the franchise's multimedia presence. While Okayu has not achieved the mainstream recognition of some contemporaries, his work on Bludgeoning Angel Dokuro-chan represents a distinctive voice in early 2000s Japanese comedy light novels and anime.