Masaki Hiiragi is a Japanese manga artist known for work in both adult and general demographics. Hiiragi made a professional debut in 2004 with the work Kuro-kun Karei na Nichijō, published in the magazine Shota Mimi LOVE vol. 6. This debut marked the beginning of a long-running association with what would become the signature series, the Kuro series.

The creator is most widely recognized for the Shōnen Maid Curo-kun series, which began with the adult-oriented installments Shōnen Maid Curo: Dorei-hen in December 2005 and Shōnen Maid Curo: Chigyaku-hen in July 2007. The series continued with additional entries, including a later volume subtitled Ninshin-hen published in September 2013. In 2008, Hiiragi began work on the Kakuryo no Ko series while also serving as the lead organizer for the doujin circle Cafe Unlimited.

Beyond original creations, Hiiragi undertook adaptation work, most notably illustrating the manga version of Phantom: Requiem for the Phantom. Based on the original story by Nitroplus, this series began serialization in Monthly Comic Alive magazine in February 2009 and was subsequently collected into three tankobon volumes. The artist’s body of work is characterized by a focus on specific genre categories, with the early career centered on adult-oriented publications before expanding to include general-audience adaptations of established visual novel properties. The artistic identity is closely tied to the long-running Kuro series, which spans multiple volumes and remains a central part of the creator’s bibliography.