|Attack Element: Physical||Collapse Effect: Boss|
|HIT * 100%||State Resist: Fallen|
|State Resist: Scared||Stun * 50%|
|State Resist: Paralysis||State Resist: Paralysis|
|State Resist: Confusion||State Resist: Sleep|
|State Resist: Flustered|
Sweetheart is a Joy Mutant that appears as a large, outstretched beast with spider-like appendages and a crooked neck. Sweetheart has multiple projectiles sticking out of its form and long, black hair obscuring its face. It is primarily controlled by Dr. Yado to do his bidding.
It first appears early in the game when it kills Bolo's gang. It appears again when Buddy tries to save Rando from falling down a pit; killing Bolo and stopping him from molesting Buddy. After defeating all 6 warlords, Dr. Yado commands Sweetheart to fight Buddy, but the fight is interrupted by Buzzo.
- Pre-Area 1 (cutscene)
- Road to Crossroads 2, only after killing 6 of the 7 available Warlords and choosing the "hold on tight" option. (cutscene)
- Ending (battle)
When you eventually battle Sweetheart near the end of the game, it's best to use Mend more than healing items if you can, since Sweetheart is scripted for Buzzo to eventually stop the fight. You should use your healing items for the fights afterwards.
- Strangely when it moans, it sounds almost like a female voice. This could mean that Sweetheart was one of the few remaining females before it turned.
- The song that Dr. Yado plays immediately before the fight is called "The Finale". This song could possibly be a command for Sweetheart to attack.
- Sweetheart is actually possible to defeat, but apart of getting joy and exp, you only cut the part when Buzzo stops the fight.
- Sweetheart is Dingaling's favorite Joy Mutant. 
- Sweetheart is not Buddy's mom, but someone else not introduced in the game. 
- The file name for Sweetheart's in-battle sprite is called Battler_Gale.png, which suggests that its name was Gale when it was human.
- In the LISA Zine, Dingaling stated that Sweetheart is not necessarily female, and that its gender is irrelevant. Sweetheart is more of a pet name than a gender indicative one.