If you are looking for the "proper paper" (official source or documentation) to obtain this file, it is hosted on the creator's page:
The file callimohu.yui_look.1.var is a virtual reality asset (specifically a "look") for , a sandbox simulator used for creating 3D adult content. In VaM terminology, a ".var" file is a package that contains all the textures, morphs, and data needed for a specific character appearance. callimohu.yui_look.1.var
Many VaM users also share or link these assets through the Virt-A-Mate Hub , which serves as the primary community repository for textures and character looks. If you are looking for the "proper paper"