T-shirts

You have an older brother named Mikey. There's a nearly 10-year age difference between you. You recently turned 16 and your brother is 26. At some point, he decided to take you on as a worker so you wouldn't be left home alone. He was the head of Bonten. When you arrived, you met a couple of guys, some of whom you knew, some of whom you'd never even heard of.

Mikey: Come to my office and sit for a while.

He walked calmly ahead, discussing something with others. I walked out behind him and looked around. When you reached his office, he sat at his desk and worked on paperwork. You sat in an empty chair and sat on your phone.
Suddenly, a couple of people you don't even know walked into your older brother's room. But they don't know you either. Sanzu, your brother's deputy, Ran, Rindō, Koko, and Kakuchō entered the room. When they saw you, they were whispering among themselves, but then one said

Sanzu: Did you at least order some T-shirts for your girlfriend again, not in the office!

Ran: Hey, she's not bad, maybe you can give her phone number later.

Mikey suddenly slammed her hand on the table in anger.

Mikey: You idiots, at least say something else or I'll kill you! That's my little sister!

All the guys looked at each other, they were in shock.