Jevil is an optional, incredibly difficult secret boss found in the Card Castle basement in Chapter 1. He is known for his chaotic attacks and relentless bullet-hell patterns. Defeating him is a true test of skill and patience.

Phases & Attacks:
- Phase 1: Jevil uses several unpredictable attacks, including spinning scythes, carousel horses, and diamond projectiles.
- Phase 2 (Low HP): His attacks become even more frantic and complex, often filling the screen with bullets. He'll use his 'Chaos, Chaos!' and 'Metamorphosis' attacks.
Strategy:
- Pacifist Route: To spare Jevil, you must use specific ACTs to tire him out. This involves Kris using 'ACT' to 'Hypnotize' or 'Pirouette' him, while Susie and Ralsei defend or use 'Pacify' (Ralsei). You need to perform these actions many times while surviving his onslaught. This is generally harder than the violent route due to the sheer number of turns required.
- Violent Route: Focus on dealing as much damage as possible with Susie's 'Rude Buster' and Kris's 'FIGHT'. Use Ralsei for healing. This route requires excellent dodging skills and efficient TP management for healing.
Rewards: Devilsknife (Susie's best weapon) for violent route, or Jevilstail (powerful armor) for pacifist route.