About a third of the way through this volume, I became reasonably certain that I reviewed the anime version of this title and that it didn't leave much of an impression on me. This absolutely turned out to be the case, and I'm delighted to say that the manga is much more fun. The reason could simply boil down to the book being better than the adaptation, which does feel very likely – the anime version ran in fifteen-minute episodes, whereas the manga's first volume is only three very lengthy chapters (plus an unrelated short story). The difference this makes is remarkable; the long chapters allow creator Minami Mizuno to truly show us who the characters are. Yes, they can all still be defined by their own little quirks that may or may not work out for them, but the extra time getting to know them and watching them interact with each other makes a significant difference.

The cast of characters consists, thus far, of four boys and three girls. On the boy side, there's enthusiastic sadist Keiichi, hapless Natsuki, playboy Matsunaga, and otaku Tsuyoshi, and together they're a mismatched bunch. As the volume goes on, Natsuki falls hard for Anna, a quiet girl he met on Christmas Eve and later realized went to his school. Anna is guarded fiercely by her misandrist friend Mari, and Tsuyoshi's cosplayer girlfriend Yukirin rounds out the group. (Keiichi starts the series with a girlfriend, but he, Matsunaga, and Natsuki are all dumped at Christmas in the first chapter.) While a couple of side characters have appeared – such as Keiichi's older brother, who is a teacher at their school – the action is contained within this group for the most part, with the four main boys taking up the bulk of the story.

The story itself is very much a slice-of-life piece with comedic trappings. It hits a lot of the traditional story beats, such as having to study for exams and Christmas dates, but it doesn't linger on the plot itself – the draw here is the characters and how they interact with each other. The emphasis is on the contrast between the core group's personalities. Natsuki is more or less the straight man, following a “normal” high school boy trajectory (for manga, anyway) as he pursues Anna and kind of bumbles through life. Matsunaga's playboy tendencies – and the first chapter suggests that he may not be quite as successful as he thinks in that – are generally played for laughs, although he's also behind the most problematic moment in the volume. Keiichi's sunny personality contrasts well with his incredible enthusiasm for sadism and his perpetual quest for a girl who wants to be the M to his S, and his character works because he's also very, very clear that he wants things to be consensual. That's a really nice point to have him explicitly clarify, because it allows readers to see that kinks are fine if both parties are into it in a more PG way than we typically see. Tsuyoshi gets the least development of the boys in this volume, although his upset at Yukirin dying her hair orange for a specific cosplay suggests that he may be pickier than is strictly good for him.

The scene I mentioned above where Matsunaga's actions create an uncomfortable situation also involves the most difficult character in the book: Anna's friend Mari. Mari is well aware that she has an abrasive personality, which isn't in itself a problem – the issue is that Mari has no interest in being anything but difficult. It's clear that this comes more from a place of fear than anything else – in a flashback we see that Anna is the only person who has ever accepted her without question, and Mari says that she's in love with Anna. She therefore seems to see any and every boy as a threat to her relationship with her, and while her actions are understandable, they are anything but sympathetic. She's much more tolerable here than in the anime because we can't hear her shrieking and screeching (unfortunate vocal decisions were made in the anime), but that doesn't do anything to make her likeable. None of this is to say that Matsunaga forcing a kiss on her is at all acceptable, and I find myself concerned that there will be an attempt to turn them into a couple. Not that her spitting on him is all that wonderful, either; suffice it to say that they bring out the worst in each other and that their scenes together are mercifully few, because they bring down the book.

On the whole, Rainbow Days is off to a decent start. The included short story is an interesting enemies-to-friends-to-lovers tale that does a good job of telling a complete story with a closed cast of characters, and if the footnoted Hokkaido dialect is a bit odd, it isn't an impediment to reading. The art is solid, if unremarkable, in general, and the translation doesn't rely too much on slang that will quickly become dated, which is nice. This isn't a groundbreaking start to an astounding series, but it is a cozy read for the most part, and that's enough to merit at least a second volume.