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's musical approach for Xenogears was to blend traditional music with Celtic influences, aiming for a balance between accessibility and depth in his composition.