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. The World S Finest Assassin Music

: Features various OST playlists and unofficial remixes/covers. : A signature track reflecting the dual nature

: Included in the single Dark seeks light / Sanbunteki LIFE released by the Lantis label. Ending (ED): "A Promise" Artist : Performed by Aira Yūki . The World S Finest Assassin Music

and "Reincarnated Beat" : Instrumental pieces used during critical transition scenes. "Time with Dia" : A softer, character-focused theme.