ReiYuuichirou

ReixYuuichirou is a het ship between Rei Hino (aka Sailor Mars) and Yuuichirou Kumada in the Sailor Moon series.

Canon
In the classic anime Yuuichirou had a huge crush on Rei. She does warm up to him later on after he risked his life for her.

Like many anime-only characters that appeared in season one he is not mentioned in later seasons.

Fanon
It is a less common ship.