A third of "Yggdra Union"'s soundtrack is dominated by Shigeki Hayashi-composed character themes, which are important in the presentation of the battles. When a clash starts, the attacker's theme song is the background music used for the entirety of the clash, and, when a player-controlled character is the attacker, the pacing of the music is dictated by the mode; in Aggressive, the music will speed up, in Passive the music will slow down, and when Neutral the music will play normally.