Tetsuo Ishi, a 20-year-old with blonde hair, is Ayase Yukiya's cousin who betrays him by orchestrating his sale at a sex slave auction without consent. This act arises from Tetsuo's urgent need to settle his substantial debts, resulting in Ayase being purchased for 120 million yen by the loan shark Somuku Kanou. Tetsuo's self-centered nature drives his choices, prioritizing financial survival over familial bonds or Ayase's well-being. He consistently focuses on his own needs and struggles to calmly evaluate his surroundings or the consequences of his actions. His mother, Ishii Rikako, is Ayase's aunt, though their family dynamics remain unexplored beyond this betrayal.