Lonelyhearts, A.K.A. Experiment 378, is an illegal genetic experiment created by Jumba Jookiba. She is designed to induce unrequited love in males.
Experiment 378 was the 378th genetic experiment created by Jumba with Hämsterviel's funding. She was designed to induce unrequited love in males.
378 and the other first 624 experiments were deactivated and smuggled to Earth by Jumba during his mission to capture Experiment 626.
All of the experiment pods were released and scattered across the island of Kauai.
Presumably, 379 was activated and tamed by Lilo and Stitch and afterwards was captured by Leroy to be destroyed in the stadium. She along with the other 625 experiments before Stitch fought the Leroy army only to face near complete defeat until Stitch played "Aloha Oe", shorting out the clone army.
Lonelyhearts is a light yellow Angel-like experiment with long curly hair, longer Stitch-like ears, a heart-shaped marking on her chest, an upside-down heart-shaped marking on her back, Manners-like legs and tail and a dress-like body with a long skirt.
Lonelyhearts uses her spell to cause men to fall in love with her at first sight, and then purposely rejects them. Her victims become incredibly depressed and sulk around instead of contributing to society (thus the downfall of civilizations). They also continue to pursue 379's affections in sappy ways (such as writing her songs/poetry), will fight each other over her, and will do anything she says.
Lonelyhearts controls men under her spell.
Women are immune to her spell, has no physical defenses.
- Lonelyhearts is described by the experiment computer screen that says "Experiment 378 Primary function: Induces unrequited love in compatible lifeforms".