I've seen people comparing it (sometimes negatively) to Re:Zero, Higurashi When They Cry or even Steins;Gate, Erased or Madoka Magika, because it's built around a time travel reset. It's closest to Re:Zero in how the plot works, but the tone and setting reminded me more of Higurashi. Both are "everyone's doomed" horror-like stories in an isolated, rural, friendly-looking Japanese community with sinister gods and a lot of bad endings. Higurashi has the remote mountain village of Hinamizawa, while this has the island of Hitogashima with a population of 700 people, getting by on tourism and fishing. Personally, I really liked it. This might even be my favourite of those shows I just listed. Re:Zero is rightly famous and extremely powerful, but in a way that made it hard for me to get through and I ended up ditching the show. Higurashi is utterly without parallel and I think it's amazing, but it dragged itself out stupidly and turned to garbage with Gou (at the end) and Sotsu. Steins;Gate has likeability obstacles (i.e. Rintaro Okabe in the early episodes). Madoka Magika for me is in the same box as Neon Genesis Evangelion, i.e. a massive landmark that changed the industry, but you won't catch me rewatching it or going near the sequels/remakes. Erased is definitely good, though.

Our hero, Shinpei Ajiro comes home to Hitogashima for the funeral of his childhood friend, Ushio Kofune. There, he hears about doppelgangers. If you see a copy of yourself, you're going to die. This sounds implausible... but then he sees two of Ushio's little sister Mio and the copy has a gun. A couple of bullets later, a resurrected Shinpei is travelling to the island again and re-experiencing scenes that have happened once to him already.

For a while, it's a supernatural mystery. We've no idea what the hell's going on. Those doppelgangers (aka. Shadows) can copy your appearance and memories, impersonate you and then spread the infection to your family. When copying someone, they'll also try to kill the human originals. People would realise something wrong if two of you were running around. They can even copy inanimate objects, to some extent, and there will be major surprises in how they operate, what they're capable of and how you can expect them to behave.

"It's like a disease endemic to this island. Not many have seen it in recent times, but it was quite common before the war. If ya were taken with the shadow sickness, ya'd start seein' yer 'shadow'. Those who saw their shadow died. They were killed by it. And it pretends to be who it killed, then it kills everyone else in the house. Least accordin' to legend. So the afflicted would go to Hiruko to be cleansed. That's what my gramps used to say."

The show's not afraid to do goofy comedy. Underwear colour becomes a plot point, to distinguish the two Mios. Allegiances can be deceptive. Once, we see three of someone simultaneously. Is it possible for evil to be innocent, adorable and funny, or is there something we don't understand yet? Eventually, though, we get a handle on the show's mysteries and the story turns into a fast-paced action horror thriller. There's a limit to the looping (which the baddies can also do, incidentally) and there's no guarantee that any of our heroes will survive.

Would this show stand up to rewatching? Not sure. A lot of great shows don't, e.g. Death Note, which is driven entirely by its evil plotting and wouldn't work as strongly second time around. Re:Zero is so strong that you could watch it again and again without losing anything. This... well, it doesn't fall apart (Higurashi), it has a proper ending that doesn't take 80+ episodes and/or 45 novels to reach (Re:Zero) and it doesn't poison the well by trying too hard to be unpleasant (Madoka Magika, Neon Genesis Evangelion). Personally, I think I could rewatch it and the characters would carry me through, despite now knowing the answers to all the mysteries. I find Ushio's contradictions fascinating, while she herself made me laugh and got a lot of character development. I like the sympathetic Shinpei-Ushio-Mio triangle. The supporting cast can be amusing and silly, but you never know when one of them might produce a gun and shoot you (or your friend) in the head.

This show went into Disney jail and got less attention than it deserved. Disney Platform Distribution sat on it for nearly a year before releasing the whole show as a "Hulu exclusive". A live-action movie adaptation is scheduled for 2027, though, which I'll definitely be watching. It's not as character-focused as many time loop anime, instead being driven more by plot, mystery and action, but I'm happy with that. It's got a foot in both the horror and SF genres, with the Shadows being intriguing and the mysteries having complicated and really dark answers. Those get pretty wild (and, again, have similarities with Higurashi.) I enjoyed the show. If comparing it with other anime, I'd almost liken it to something like the vampire series Shiki rather than those time loop series I mentioned. Definitely underrated.