Trap, born Stear Boots, belongs to Doma's Boots clan—a family of thieves functioning as a community-focused guild through ruin excavations and treasure hunts. Generational ties link his clan to Clay's family since their great-grandfathers' era. He adopted his nickname to distinguish himself from his identically named grandfather and deter kidnappings, resenting the man for his harsh upbringing.

As the thief in Pastel's adventuring party, Trap defies stealth conventions with vibrant attire and flowing red hair. He battles using a slingshot and leverages agile climbing skills to navigate terrain. His troublemaking nature features profane language and gambling habits. Though carelessness frequently lands him in traps, his pragmatic outlook counterbalances the party's idealism. He playfully mocks Pastel yet displays jealousy toward her male suitors, implying hidden affection.

During a debt-repayment mission collecting hot spring water, Trap secured a deal granting their quest-giver 40% of treasure finds. His impulsiveness provoked a tentacle monster by stealing a cave ruby, and later he triggered a trap separating himself and Pastel from allies while searching for the missing Rumy.

He once wore green tights, mistakenly considered a family heirloom, but discarded them after learning the truth; Pastel noted his improved fashion sense afterward. His magical aptitude remains minimal.

Subsequent events involve Trap's father returning from Mount Terrason with a white dragon jewel mirroring Shiro's. This prompts Clay, Pastel, Rumy, and Shiro to investigate connections between the gems and Shiro's origins, though Trap's participation in this quest is undefined.