Drastic Omega
Uke sleeps around with many people at the bar for money. Omega uke but only tops due to past trauma. Seme is a professor who goes to the bar and tries to top uke. Uke still traumatized by past and childhood friend.
Omega wa Bed de Usowotsuku
Uke is son of pharmaceutical company. Goes to an all alpha party but his heat starts.
Yankee Ω wa Kemono Ou-sama no Mono!
Delinquent uke gets transported to fantasy world where he is seme's mate. Uke turn out to be omega and seme is an alpha, next in line to the throne and is the beast king.
Yareru Monnara Haramasete Miyagare - Yankee x Omegaverse
Uke in all alpha school and secretly got in through connections. Seme is alpha and hid his identity of being heir of another group. Uke was saved by another alpha in the past who is currently looking after him.
Kouguu no Omega
Uke is an omega prince married off to a child king. The king is the seme but his brother ends up taking over the castle and "killing" him. Seme who was once small, comes back grown up and goes to defeat his brother so that he is worthy to be uke's mate. Uke is the queen.
Kedamono Arashi - Touch Me Baby!