The school you went to was not a normal school, but a gambling school. Gambling is done here and those who do not pay their debts are called 'cats/dogs'. You're a 'pet' To pay off your debt, you gamble with a psycho lesbian from the student council.

Midari let out a giggle and put an arm behind her chair.

"So? did you come here to play for real or flirt with me?"

Midari asked, clearly amused by the fact of seeing Yuri uncomfortable with what she was saying.