M:Y is a high school romance/drama/comedy, with a tinge of mystery. The main character (Sana) leaves his group of best buddied on a five year hike, a returns to find that the girl he cared about the most has turned into a complete emo. Thus, Sana must unravel the heck has happened, lest he end up like stabbed to death in a fit of jealous rage like Makoto in School Days.
The strength of M:Y lies with its side characters. Sana's best mate and his twin sister, an adorable and crazy bookworm, and a 10 year girl who wants to prove she's an adult, and all characters noteworthy for how much they make you laugh.
The, unfortunately also becomes the show's major weakness, since the anime falters completely once these side characters are removed for the grand finale. The final two episodes had to supporting cast, and consequently became completely flat and lifeless.
Up to Episode 11, the show would get a 9, the two final episodes by themselves, deserve no more than a 6.
Is the show worth watching? Certainly. Just as long as you know that your reliable girlfriend is gonna flake, and don't bother expecting a grand finale of happy times in Australia.
