Kogare Ouji no Dilemma
Uke gets tricked into debt by teacher. Seme buys uke and wants him to be his lover.
Senya Ichiya Romanesque
Uke met seme prince a long time ago and were childhood friends. Years later, uke's sister has a marriage interview to marry seme but seme actually liked uke for al these years. Uke agreed to be seme's wife when they were younger and seme wishes to follow through with promise and marry uke. Sister is aware and doesn't care.
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.
The Prince's Collar
Uke is a human prince who gets saved/bought from prostitution house by beastman seme.
Rebirth