Shirabii made his major debut as an illustrator in 2010 with the light novel Probably Impossible to Talk Her Down written by Shoji Urema and published by Smash Bunko. He drew the ending sequence cards for Episode 3 of the TV anime Boku wa Tomodachi ga Sukunai in 2011. He also illustrated the Boku wa Tomodachi ga Sukunai: Shobon! spin-off manga published by Media Factory in 2012.
After working on multiple light novels, his first major success was The Ryou's Work is Never Done!, a light novel series written by Shirow Shiratori and published by GA Bunko. Next, he worked as the character designer and illustrator for the character Tomoe Gozen and various other "Craft Essence" in the extremely popular smartphone RPG—Fate/Grand Order.