1: friends, seme likes uke first but uke doesn't realise
2-3: uke wants to separate an annoying guy from his best friend aka crush since they got close. sets up a trap but got caught in his own trap, his best friend seme has a crush on uke; seme, uke and annoying guy had 3some. in the end seme and uke is together without annoying guy
4-5: foreign prince exchange student x pe teacher. prince's country's cultural is to get penetrated in the ass.
Bokura No Mitsudomoe Sensou