Meixing Long is a supporting character who appears in the 3x3 Eyes anime. She is the younger sister of Steve Long, a colleague of the protagonist Yakumo Fujii in the monster-hunting business. Meixing is established as a superb martial artist, skilled enough to initially overwhelm Yakumo in their first encounter.

Her role in the story begins when she witnesses the explosion of her brother's apartment. Searching through the rubble, she discovers a fragment of the Statue of Humanity, a significant artifact. This event motivates her to search for her missing brother and the people responsible for the bombing. Her quest leads her to cross paths with the main characters, Yakumo and the mysterious Sanjiyan unkara, Pai. When they first meet, she attacks and beats up Yakumo, mistaking him for an enemy.

Throughout her appearance, Meixing develops a romantic interest in Yakumo. However, it becomes clear that Yakumo’s attention and affection are directed solely toward Pai. Recognizing this unrequited situation, Meixing ultimately decides to leave and study as an exchange student in England. This decision marks the end of her active role in the anime's storyline, showing a mature acceptance of Yakumo's feelings for Pai.

Regarding her relationships, her primary connection is to her brother, Steve Long, whose disappearance she investigates. She also forms a brief but impactful relationship with both Yakumo and Pai, as they join forces to rescue Steve from a trap. In terms of abilities, Meixing is primarily known for her proficiency as a martial artist, which she demonstrates in her confrontations with Yakumo and other adversaries. Her physical appearance includes black hair cut to neck-length and black eyes, typical of her design as a young woman in the series.