A Unremarkable Teacup is one of the evolution items that is used to evolve Counterfeit Form Poltchageist into Unremarkable Form Sinistcha when used.
Obtaining
Loot
Masterpiece Teacups can be found within Ruin structures as Suspicious Block loot in Crumbling Arch Ruins, Deserted House Ruins, Hidden Bunker Ruins or Toppled Pillars Ruins.