Sheryl had to think hard to fight the girl who was in her ex-lover's lap. She was much more senior than the Girl so Sheryl couldn't just lose. No one knows and knows Abercio's habits better than him.
"Hey, beautiful sister. I'm even much younger than the boy you're sitting with right now. How can you call me aunty? I'm only 27 years old. That's too old for me. older brother." Sheryl said that she didn't accept that she was young. It was compared to an Aunt who might be older than her, for example, Aunt Charlotte. Perhaps the woman at Abercio's mother's age suited the title of aunt better than her 27-year-old self.
Hearing Sheryl's words, Akira burst out laughing.