According to Mitsuda, the music of Xenogears belongs to the traditional music genre. Though he first described it as stemming from "a world of [his] own imagining" rather than any specific country, he has also claimed a strong Irish or Celtic music influence. His musical approach for the original soundtrack was to insert Celtic influences into "easy-to-listen-to" pop tracks rather than making either "dense" Celtic music or simple background music.
Mitsuda, the composer of Xenogears' music, initially described it as originating from a fictional world rather than any specific country. However, he later acknowledged a strong influence from Irish or Celtic music. He aimed to integrate Celtic elements into "easy-to-listen-to" pop tracks instead of creating either complex Celtic music or simple background music for the soundtrack.