Manga

*******SPOILER**********

It's a wee bit different. Sayaka has a twin brother. There are only two kids in the movie: Miura and Hotaru. So you don't even see like a "relationship" forming between the kids, because the other two kids are missing. And Tomoki is supposedly the reincarnation of Sayaka's brother. Oh yeah, I forgot if it was in the manga, but Aya recorded a video of her and Tomoki in her cellphone supposedly the morning after they "did it." That's how Mizuki finds out in the movie that Tomoki "cheated" on her. Let's see... what else? Adam didn't overdosed himself with drugs (from what I understand, compared to the manga), the Adam in the movie committed suicide by a "car accident," supposedly to follow his lover. And in the movie, the connection between Mizuki and Sayaka is more than "reincarnation." It's something to do with the necklace that Adam gave to Sayaka and then, Tomoki gave to Mizuki (I forgot if these were all in the manga, but I don't think so). Also, don't expect a lot of "comedic act" like in Ai Yazawa's manga. The movie is so much slower. There are some funny parts, but barely... probably only when Tomoki makes funny faces and idiotic comments. Also, the movie has a lot more foreshadowing because it's a movie. Like for example, in the beginning, Mizuki tells Adam that she's heard "that song" before because her dad used to sing it to her (although in the manga, Mizuki never heard that "tune," but rather she came to like it until she heard it on the radio.) Yeah, I think that's pretty much it.