There are some adaptations where you can make an educated guess that things are being left out in the transition. Reborn as a Polar Bear: The Legend of How I Became a Forest Guardian's first manga volume is one of them. The story began life as a light novel series by Chihiro Mishima, and while Houki Kusano's manga version does a decent job of letting us know about the world and the characters, there's a lack of cohesive story flow that brings the volume down. It's a cute concept (or rather, variant on its isekai subgenre), but it never quite comes together the way it needs to in order to feel like a satisfying book.

The story is fairly basic as far as the rebirth variant of isekai goes. Kumakichi Kumada was a run-of-the-mill twenty-eight-year-old man who enjoyed climbing mountains, apparently without adequate safety gear. When he slipped on a climb and fell into a crevasse, he was Reborn as a Polar Bear in a pseudo-medieval fantasy world populated by both humans and beast people. The latter are discriminated against by the former, especially the wolves, and when Kumakichi stumbles across a large group of human knights fighting a single teenage wolf girl, he steps in to save her. Fortunately his new physical strength as a polar bear allows him to dispatch the villains with ease, and the girl, Lulutina, is beyond grateful. When Kumakichi realizes that she and her sisters are the only survivors of their clan and are eking out a bare existence in a cave, Kumakichi decides to use his Japanese know-how and polar bear power to help them out, basically nominating himself for the role of their guardian.

As with many stories where a relatively young man becomes the de facto guardian of younger girls, there are some uncomfortable moments within the story. Most of them sort of slip right past Kumakichi, in part because all three of the oldest girls are still at least ten years younger than him, but also because he doesn't understand wolf customs. That said, there's still something awkward about seeing Lilitina lust after an actual bear, talking or otherwise, and Kumakichi's inner monologue about how attractive he finds both Lulutina and his new set of more impressive genitals is likewise kind of off. Mostly this is because the story really doesn't need a sexual aspect to be interesting – while it makes a certain amount of sense that Kumakichi would notice his new body's differences from his old one and that he might have the same preferences as a bear that he did as a human because he's very clearly the same person inside, the addition of the girls' physical attraction to him in this body is more of a distraction than anything, and may make some readers who would otherwise enjoy the story uncomfortable.

It also doesn't help that while artist Houki Kusano draws some very nice wolf girls and forest scapes, they aren't particularly great at drawing bears. Since the main character of the book is, in fact, a bear, this understandably has a negative impact on the artwork overall. It's not that Kumakichi needs to look hyper-realistic, it's more an issue of him looking awkwardly like a combination of an actual polar bear and an attempt at making him something more cuddly. His height also seems to fluctuate, which can be distracting. The fact that the other, non-verbal bear who shows up in the volume appears to have six legs is also a bit odd; it's very possibly a piece of world-building that was more fully explained in the original novel, but the lack of context here means that there's a moment of wondering if the artist just messed up or didn't do a great job of trying to show rapid arm movement.

For all of its issues, Reborn as a Polar Bear: The Legend of How I Became a Forest Guardian isn't a terrible book. It feels as if we're missing quite a bit of Kumakichi's internal monologue in places (why introduce himself as a cheapskate?), but it does work well enough that we get a good idea of what's happening and where the story is likely to go from here. There's potential for a couple of different relationships to grow from Kumakichi's interactions with Lulutina and her sisters, be that parental or something more romantic with one of the older girls, and the elements of how to survive in the wilderness with very few tools at your disposal are interesting. There's a sense that there's a good, lighthearted story waiting just a few books down the line (or in the original novels), making this feel like a longer-than-usual prologue. If you're willing to wait it out or if you just really love polar bears or wolf-eared girls, there's enough to make it worth your while. If you're starting to sour on the genre, however, this is probably an easy pass.