Tris is a mysterious creature possessing cat-like ears and long blonde hair with bangs. Their green eyes feature distinctive orange pupils. As an interdimensional entity, Tris holds intimate knowledge of the dream world Traumerei and the desire-born creatures emerging from it, known as Desaria or Weirds.

This entity serves as the bestower of the "Knocker Up" ability, granting this power to individuals including Ryuuhei Oda, Rena Mouri, Rando Furukata, and their companions. Tris initiates the connection by biting Ryuuhei's leg, triggering unusual dreams and enabling him to perceive supernatural entities. This act directly leads to Ryuuhei's recruitment as a Knocker Up tasked with combating the creatures threatening Shibuya.

Tris maintains connections to other Knocker Ups beyond Ryuuhei, such as experienced fighters Jessica Clayborn and Aruto Fushibe. Their relationship centers on enabling these individuals to transition between reality and the dream world, while the exact nature of Tris's motivations remains unexplained.