A young man who serves for the Vanguard's espionage division inTales of Symphonia Knight of Ratatosk, but only because his love interestAlicejoined them. He is so madly in love with Alice that his Mystic Arte involves going into a frenzy over his favorite picture of her being destroyed. Decus is also known for being obtuse, thinking that Alice's insults toward him are signs of affection.