Slug Girl

A monster who may give off a humanoid appearance, but in reality, the Slug Girl is a monster evident by her lower mucus-covered membrane. She is the second monster Luka encounters, and is able to fend her off with salt, a slug's weakness.

Encyclopedia Entry
"With her body that of a soft slug, weak attacks will get stuck in her mucus covered membrane. The Slug Girl's behavior is to take walks at night and attack any men she encounters. Like most monsters, her staple food is male semen. Using the lower half of her body, she carefully stimulates her catch to feed.

''Once she catches a male in her slimy mucus membrane, they are forced to ejaculate with surprising ease. With that, she is able to feed.''

''In addition, if the Slug Girl particularly likes her catch, she will use the genitals in the slug half of her body to mate with her prey. Using the same techniques as feeding, she will force the male to release just enough semen for copulation.''

Once a suitable male has been found to copulate with, the Slug Girl will continue to use him as both a mate and a source of food for the rest of his life."

Battle Overview
Being a slug and Luka's current stature, his attacks simply do nothing to her. She then climbs onto Luka, which requires Struggling to break free. Realizing his physical attacks do nothing, he decides to throw salt. Lowering her HP enough, she flees.