KKM puts a fun spins on the "transported to an alternate world" theme that's rather common in anime.
Yuri attempts to save a former classmate from some bullies, instead, he finds himself getting dunked into a toilet! To make matters worse, he's sucked INSIDE the toilet. He finds himself in an alternate world and these people think he's the new demon King! I love this show, it cracks me up. Some more conservative minded individuals may find insult at the prevalence of gay male relations in the show. However, the relationships are treated lightly and used for a comedic effect. KKM is more shouen-ai than hardcore yaoi.
The colors are bright and cheerful, typical for the modern CG animation techniques used today. The character designs lean toward "pretty-ness", fans my find it to be a bit of a bushmen (pretty boy) fest.The music is, mediocre, nothing overly fantastic, the OP and ED themes will grow on you.
The Plot isn't serious and needs to be taken with a grain of salt. Granted, later on, there are more serious moments in the plots and in some of the characters' back story. It isn't overly violent, nor is there a lot of foul language, but this show isn't for the kids, it's rather laden some subtle (but tasteful) innuendo.
KKM is a fun, light hearted romp that anime fans will love, provided they don't try to take the show too seriously.