Lemmy Miyauchi, formally Lemmy Christopher Helen Miyauchi, is a half-Japanese, half-American individual born in California. Her early childhood was spent in Japan before relocating to America; she later returned to Japan. This background results in an imperfect command of Japanese, frequently causing mispronunciations and mixed-up sayings, though she occasionally displays unexpected wisdom. She habitually overuses the word "fantastic" in conversation.

Physically, Lemmy possesses blonde hair styled in a shoulder-length ponytail with spiky bangs, blue "tareme" eyes, and a distinctive fang. Notably tall at 174 cm, she stands as the only main character taller than Hiroyuki Fujita. Her measurements are 92-59-86 cm, maintaining a slim, pale physique.

Lemmy's personality is loud, boisterous, energetic, and outgoing, often appearing over-the-top. Despite an airheaded demeanor, she is fundamentally kind, cheerful, and caring, exhibiting a "deredere" romantic side. She forms strong emotional attachments and is quick to help others.

She is a member of her school's Kyudo (archery) club and holds a part-time job. Her archery skills present a unique contrast: she excels at hitting moving targets but struggles with stationary ones. She also participates in bowling.

Family-wise, Lemmy is the middle daughter of George and Ayame Miyauchi, with siblings named Cindy and Michael. Her family relationships are generally positive, and she owns a pet.

A significant revelation in *Remember My Memories* discloses that Lemmy was Hiroyuki's childhood friend prior to moving to America. A photograph exists of them together during this time, depicting Lemmy with black-dyed hair. She harbored long-standing romantic feelings for him, culminating in a confession during the series' events. Faced with an impending relocation back to America, she proposed eloping with Hiroyuki, but he declined her proposal.