Fighters' Battle Song

Sound Yojutsu: Fighters' Battle Song (音妖術『奮闘人応援歌』) is a Sound Magic spell.

Description
While playing their biwa, the user manipulates the sound and uses it to bolster their allies' bodies and reinvigorate their fighting spirits. It can also be used to communicate orders over long distances.

Trivia

 * This spell may be a reference to "Sainō-jin Ōenka" (才悩人応援歌), a song by BUMP OF CHICKEN.