The Splash Gun, or as Kay calls it, "legally distinct, generic liquid gun that shoots out colored water" is based on the Splattershot paint gun from Splatoon. The gun is a reference to Flare's love for Splatoon, which she frequently streams, especially when joined by IRyS.[1]
Flare Blasters is based on Flare's infamous playthrough of Undertale, specifically her battle with the game's famous boss battle Sans, where she replayed the battle multiple times just to kill him.[2] Its appearance and ability are more specifically based on Sans's own laser-spewing "Gaster Blasters".
Shiranui Construction (AKA "Shiranui Kensetsu" or "Shiraken") is the construction company established by Flare in Minecraft in response to, but not competing with, Usada Pekora's Usada Construction and Minato Aqua's Akukin Construction. Out of the three construction companies, Shiranui Construction is the most recognized as a unit outside the game, with its members participating in various hololive activities, including their performance at the hololive 4th Fes Our Bright Parade.
The "walls" of the icon that gets displayed when the skill activates are themed after the four other Shiraken members: Omaru Polka (bottom), Sakura Miko (top), Hoshimachi Suisei (left) and Shirogane Noel (right).