I-pin is an assassin from Hong Kong, and speaks in nothing but Chinese. Even though this 5-year-old little girl can't speak Japanese, the 15-year-old "Adult I-pin" eventually enters a Japanese College, and despite the fact that she is one of the most promising young assassins, she will work part-time at a Chinese Restaurant ten years later. She has a crush on Kyoya Hibari, who looks like her teacher.

During times of extreme stress, she will latch onto the nearest person, and a clock will appear on her head, when it reaches zero, there is an explosion like a bomb.