It all starts off innocently enough: Makoto travels by train every day, and every day he sees Kotonoha, who goes to the same school. He is interested in her, but doesn't know how to get into contact with her. His classmate Sekai helps him to get to know Kotonoha -- but she demands payment: a kiss!
Kotonoha and Makoto start dating, but since she isn't used to be around men, their dates are stiff and forced. On the other hand, when he spends time with Sekai, there is always something to talk about in a relaxed manner. And so Sekai becomes Makoto's "thing on the side"...
And then it gets all fucked up. Makoto turns out to be a spineless asshole: he never takes the time to tell Kotonoha that they're through, leaving her dangling. Meanwhile, he gets some sort of reputation, and gets more and more girlfriends on the side (that he has sex with -- this series leaves little doubt as to what it is all about).
Then it all goes to hell, with Makoto dumping Sekai, getting back with her, dumping her again when she tells him she is pregnant (coitus interruptus ftl!), getting dumped by everyone because of this, getting back with a mentally instable Kotonoha, but then choosing Sekai after all. His excuse: "I am easily influenced."
And then Sekai kills Makoto, and she gets killed by Kotonoha in a very, very messy manner. The ending does take place aboard a rather nice boat, by the way.
Most of the episodes left us speechless, in a bad manner. There are no likable characters in this series, with the possible exception of Setsuna, but because she doesn't know everything that has happened, she is a total bitch to Kotonoha. Makoto is a loathsome bastard. Sekai is stupid, Kotonoha is too shy and demure.
I guess we finished this series because of a severe case of train wreck syndrome: you know it's going to be bad, but you just can't look away. That makes the pay-off satisfying, but I could have done without thirteen episodes of this.
I guess I should also say something about the technical execution (pun intended) of the series. Nothing to complain about I guess. The character designs are pretty nice to look at, and the voice acting is pretty good too. It doesn't stand out though -- maybe because the plot overshadows everything.
I'm not even going to summarise the good and bad points of the series. If you're going to watch this, be prepared: it's not cute at all, despite the first episode. I'll give it a 4 -- would have been lower if the total shock value of the ending wouldn't have lifted it up.