Hanazono Fantasica

Forumi is a student at Garuchin Academy, which is a place full of princes', princesses and other unique students from all over the magic realms. One night Forumi sees what looks like a shooting star but it really is Prince Shizuka coming from Hanazono to the academy along with his protector and servant Scrooge. He's come to the academy for one purpose only, while he's in the form of his shut-in older sister, he plans on searching for the best groom that would suit her!

Forumi happens to stumble onto him in his sister's form and Shizuka decides to make Forumi his guide and changes back into his true male form. Shizuka places a magical collar on Forumi that if forcefully removed it will kill whoever is wearing it. Now, Forumi has to show this weird prince around and make sure the peaceful life at the academy doesn't get ruined due to this odd and selfish prince!

(Source: LuffyNoTomo)