The Slime Girls are a boss enemy fought inside Humphrey, before fighting Humphrey himself. The Slime Girls in question, Marina, Medusa, and Molly, work together to defeat Omori and his friends. They can also be fought during the Boss Rush.
As stated before, they can be fought twice in the game, whatever the only difference is stats and rewards.
- First encounter: 5700 heart, 1750 juice, 57 attack, 32 defense, 52 speed and 10 luck (reward with 9000 exp and 999 clams).
- Boss Rush: 8000 heart, 4000 juice, 100 attack, 70 defense, 90 speed and 10 luck (no rewards).
Like most enemies, they will act differently according to their emotions:
Additionally, they will do the following actions as their heart gets lower:
- 75% left: They will turn themselves angry.
- 50% left: They will swap the party's with their .
- 25% left: They will do their slime ultimate attack, throwing all they have, dealing 40% damage, decreasing the speed, attack, and defense, and giving a random emotion to the party.
Skills that can be used when observe is used against the target are marked with .
Combo attack: [2 * a.atk - b.def] (default).
Strange gas: randomizing the party's emotions.
Dynamite:  to all party members, this will never hit right in the heart and does not have damage variation.
Sting ray: [2 * a.atk], does not hit right in the heart and decreases the target's speed by three tiers.
Swap: Swap all party members's with .
Chain saw:  three times, it will never hit right in the heart, but have a 75% damage variation.
Chain saw (boss rush):  three times on the same target, it will never hit right in the heart, but have a 75% damage variation.
Slime ultimate attack: [.4 * b.mhp] (40% maximum ), it will not hit right in the heart and does not have damage variation, also decreases speed, attack, and defense by one tier, and randomizing the emotions of all party members.
* The Slime Girls attack all at once! * Medusa threw a bottle... And it explodes! * Molly fires her singers! [target] gets struck! * Medusa does the thing! Your heart and juice are switched! * Marina pulls out a chainsaw! * Medusa threw a bottle... A strange gas fills the room * Slime Girls throw everything they have!
- 75% :
* Medusa: Hmph... You kids are more resilient than expected. * Marina: You know what that means. It's time to get serious! * Molly: Oh... I'm having so much fun~!
- 50% :
* Marina: Hey, Medusa! Are you thinkin' what I'm thinkin'? * Medusa: Yes, sister... I think it's about time we switched things up. * Molly: Just relax, children... This won't hurt a bit~
* Marina: You kids... are a lot tougher than you look. * Molly: Hmph... This is much more trouble than it's worth. * Medusa: Sigh... What a predicament... How will we feed Humphrey now?
When defeating the player
* Marina: Now you belong to us! * Molly: Hush, hush, darlings... Don't cry... You'll get used to your new life soon~ * Medusa: It's time to take apart the small one. Let's get started, dolls.
* Medusa throws a bottle... but nothing happened...
- ↑ Their unused "do nothing" skill would use this action text, another variation with the very same text exist, but with the user name (Slime Girls) being used instead of "Medusa".