Taro nodded, slightly surprised by her directness. "Yeah, that's me."
This phrase seems to suggest a humorous, perhaps somewhat embarrassing or bullying scenario involving a person (likely a male) being teased or pranked by a female classmate or peer, referred to as a "gal" in Japanese pop culture. A "gal" typically denotes a girl with a trendy, often bold fashion sense and a lively personality.
"Yeah, yeah, Mr. Serious!" she teased, sticking her tongue out. She grabbed the book and curled up in the corner of my bed, the sunlight hitting her glittery makeup.
Or if we're to interpret it more freely for a creative piece: