The Deviled Egg (イエローデビル, Ierōdebiru, Yellow Devil in the Japanese version, also known by the fan community as the Mold Devil) is the second boss of the Iris Stages in Rosenkreuzstilette.
It appears from behind the room where the player is trapped in. Pieces of itself will fly across the room, which have to be either jumped over or slid (dash for Grolla) under. Once all of its pieces are at one end of the room, it will reform itself and open its eye to fire a bullet at the player. The eye is the Deviled Egg's weak spot. Afterwards, it will take itself apart again and pieces of itself will fly across to another end of the room and repeats that pattern throughout the battle.
During Desperation Mode, it will alter the gravity in the game and flips everything up-side down. The actual pattern in which it takes itself apart is exactly the same as it was when the gravity was normal. It does this very often in the battle. Upon its defeat, the beholder Iris created in the background watching over the player's action will perish along with the Deviled Egg, burning away with purple flames as they do so.
- The Deviled Egg is a large reference to the Yellow Devil from the first Mega Man game on the NES, in both appearance and attack pattern.
- The Deviled Egg's Game Over screen makes a reference to The Legend of Zelda: Link's Awakening and its Game Boy Color re-release by impersonating the Wind Fish's Egg. The slit where its eye is can be seen.