Mikage is a Japanese writer and creator known primarily for his work as a scenario writer and planner for visual novels, many of which have been adapted into anime and manga. Born on March 7, 1980, in Odawara, Kanagawa Prefecture, Mikage began his career in the early 2000s at the game company CIRCUS. During his time there, he contributed to several notable projects, including serving as a planner and scenario writer for the popular visual novel D.C. ~Da Capo~. He was also involved with other CIRCUS titles such as Water Summer and Infantaria, often handling original concepts, planning, and剧本 (scripts).

Mikage later moved to the visual novel brand minori, where he became a central creative figure. His most famous work from this period is ef: a fairy tale of the two. Originally released as a two-part visual novel—The First Tale in 2006 and The Latter Tale in 2008—the story is a complex, multi-generational drama focused on themes of memory, trauma, and artistic creation, set in the fictional Japanese town of Otowa. Mikage is credited as the scenario writer for the original visual novel. The success of the game led to a substantial transmedia franchise. A manga adaptation, written by Mikage and Yuu Kagami and illustrated by Juri Miyabi, was serialized in ASCII Media Works magazines from April 2005 to March 2015, compiling ten volumes. A light novel series, also co-written by Mikage and Kagami, ran from 2006 to 2008. The property was then adapted into two anime television seasons by the studio SHAFT: ef: a tale of memories in 2007 and ef: a tale of melodies in 2008. The anime series are noted for their innovative and highly stylized direction, and they remain a significant work in the careers of director Shin Oonuma and the studio SHAFT. Mikage is also credited for writing lyrics for some songs within the franchise, including the ending theme Sora no Yume.

Following his work on ef, Mikage continued to develop original visual novels at minori. He contributed as a writer and supervisor on titles such as Eden* (2009) and served as the original creator and scenario writer for Supipara - Alice the magical conductor. (2012) and Natsuzora no Perseus (2012). In 2014, Mikage left minori to become a freelance writer. After going freelance, he began collaborating with the company Purple Software, where he served as the original planner, concept creator, and scenario writer for several titles, including Chrono Clock (2015), Amatsutsumi (2016), Aoi Tori (2017), and Kunado Kokki (2021). His body of work is characterized by dramatic romance stories that often blend slice-of-life elements with supernatural concepts and a strong emphasis on emotional, and sometimes tragic, character development. Through his foundational work on series like D.C. ~Da Capo~ and ef, Mikage has established himself as a significant contributor to the visual novel medium, with his narrative concepts reaching a wider audience through major anime and manga adaptations.