Shi Fen is Shi Miao's older brother; the siblings live together following their parents' divorce. He attends school, though reports conflict on his exact level, describing him as either a first-year high school student or a fourth-year middle school student.

His personality frequently manifests as irresponsible and prone to idiotic behavior, provoking physical reactions from Shi Miao. This includes engaging in schemes, hijinks, and extreme cheapskate tendencies. Despite these flaws, he demonstrates underlying kindness and genuine care for his sister's well-being.

Socially, he maintains close friendships with Zhen Kaixin (Kai Xin) and Wan Sui, relationships often involving collaborative antics or competitive one-upmanship. He also participates in basketball.

Across the series' seasons, his core traits remain largely consistent—characterized by a fear of his sister's temper and ongoing irresponsible conduct. While significant personal growth isn't prominently highlighted in the third season, his relationship with Shi Miao evolves beyond mere conflict. Episodes depict moments of cooperation, mutual understanding, or shared similarities, suggesting an unspoken familial bond beneath their combative interactions. His role within the group dynamic persists, involving escapades related to school life, romance, and food alongside his sister and their friends.