"Dark Seeks Light" from The World's Finest Assassin (English Cover)
: A version of "A Promise" is also sung by the character Dia (voiced by Reina Ueda). Background Score (OST) The World S Finest Assassin Music
: Theme singles can be found through retailers like Yumeya Club or on Apple Music . "Dark Seeks Light" from The World's Finest Assassin
and "Reincarnated Beat" : Instrumental pieces used during critical transition scenes. "Time with Dia" : A softer, character-focused theme. The World S Finest Assassin Music
: A signature track reflecting the dual nature of Lugh Tuatha Dé.
: A fast-paced, high-tension J-pop track that mirrors the protagonist's cold efficiency and inner search for meaning.