My-Otome Anime
Yuuichi does not explicitly exist in the anime as he is never mentioned by name, however silhouettes resembling him come up during discussion of Mai's past. Mai was supposedly in love with this man, according to Natsuki's version of events, and was torn by her duty to her country as an Otome, but a DVD special reveals this not to be the case.
This individual asked Mai to be his family's Otome, but Mai was conflicted by her choice of where to go after graduation, and eventually wound up becoming the Otome to the Cat Goddess Mikoto after she fell into the Black Valley.
It had been speculated that 'Yuuichi' is actually the young Sergay Wang due to having the same character designs, although this was never confirmed and the two do not share the same voice actor, while all other characters first seen in My-HiME had the same voice actor.
Read more about this topic: Yuuichi Tate