Fushigi no Kuni no Shounen Arisu

A Japanese student named Arisu gets on the wrong bus and winds up in some sort of homoerotic version of Lewis Carroll's Wonderland. The last thing you want to do in a land where people change shapes at the drop of a hat is to drop the soap and introduce yourself as Arisu (identical in Japanese to Alice), lest you start looking like one! And Arisu does, slowly but surely...

(Source: Manga Updates)