>>58590589 (OP)
He seems to wear split hakama and gardevoir (who evolves from Hachikazuki with the bowl on her head) wears the young-unmarried-heian-era-princess split-coat hosonaga.
It's probably some Japanese thing.
I've been out of anime for a while and know mostly girl's clothing, but isn't there some short version of the sashinuki-bakama pants they wear? And I think I've seen apprentice samurai from this era in media wearing them.
It honestly looks like he has layered hakama (which incidentally is also the style with hosonaga. It ties him to Gardevoir's theme.)