I feel the need to write this review to offer a bit of an alternative opinion to what seems to be the general consensus that this is a great drama.

I'm not sure what this was trying to be or what message is trying to convey. I didn't find it very entertaining either.
It started with an interesting premise but it went downhill very quickly.

One of my main problems with this drama are the plotholes. There is really no explanation on how things work, the main character is the one deciding what things are to be left or changed and we have to take it at face value. Who knows, maybe her friend Fuku-chan was actually not supposed to have a child, we'll never know. But that's the main problem, who decides what has to happen and what not, who decides what is good and what is bad. Maybe she saved her annoying teacher from being wrongly accused in the train situation but maybe later he killed his wife. We don't know, we just have to accept FL is somehow omnipotent and her choices are the best course of action. Somehow she also knows what to do or not to get shiny points for her next life.

It was generally passable until the friend Mari is also introduced as being in a repetition of her life, at that point I started to question if most people going by that logic are repeating lives or what are the rules on who is allowed and who isn't. Everything was already hold by a very fine thread but when the story line with the plane is introduced it was made so much worse. For starters why did they have to save all that people? They just decided so. Again, there is never an explanation on fate, morality or anything. One could argue that by them focusing all their energy and time to be pilots they missed making so many memories with the friends and enjoying life to the fullest, or that that plane crashing was meant to happen, or, and here it comes the biggest of them all, if the friends died in the plane, shouldn't they also be in their lives repetition or maybe they would have crossed the other door and reincarnated into something else in which case their deaths in the "repetition" timeline of the FL and Mari would be set to die no matter what since they wouldn't exist as humans or as themselves anymore. It's just never explained and it makes no sense.
The writers basically decided some people where allowed to be main characters, meaning people that could repeat their lives and the rest are just the puppets that follow a specific pattern.

If you have watched Groundhog Day (1993) and you enjoyed it you might like this, if you don't like a plot that pretty much repeats over and over I would say avoid this, it gets annoying, especially since the only repeated events in the life of the FL are the same ones EVERY single life with minor differences in general and a different career. It's a chore and the story is not so worth it. There are so many details in her career progression in each of her lives and what is the point? Especially the one where she's a producer.

I found it kind of stupid to go for the capitalistic stereotype of what is considered success when the FL only changes her career in each repetition and that somehow gives her different outcomes of what animal the guy in the desk tells her she's going to be in the next life. I guess we all should be doctors apparently. Equally stupid that something as silly as that guy disrupting the coming of age ceremony was full of comments about how he was going to be a microorganism in his next life. And it's not even the disrupting, is the fact of his aesthetics as well, it was very on the face of "if you don't dress society approved and behave how japanese society dictates you'll loose points at reincarnation", same kind of sentiment was shown when Mari says in her first life she was a gyaru for a while. Excuse me? If it had been done in a very funny way I could have taken this afterlife based on capitalistic success and japanese morals entertaining enough, but it falls way short of that.

It was also convenient that the four of them lived single their whole lives, I guess because the writers knew they wouldn't be able to handle the story if there were partners and children involved, so only the background characters were allowed that kind of progression.

I'm assuming part of the comedy in this show is supposed to be the way they accentuate the roundabouts of Japanese communication, I get it really, but I just simply didn't find it funny, I found it as frustrating as it is in real life.
This also brings me to the fact the FL was not really a very likeable person and there is not much of a change in her all throughout. Sure, she says at one point she started doing the things to be nice not for the points but it doesn't change the fact she's doing exactly the same things and we're not really being shown anything new.

Overall I can't recommend this drama, watching too much repetition already felt such a waste of time, it's only a comedy in the sense it's not a melodrama and the story isn't that engaging. Some might say it's ultimately a story of friendship and while yes partially it is, it's questionable when in most of the FL's repeated lives she didn't spent that much time with the friends (she even complains to them in one of them because they visit her too much) and it's not shown like she misses them that much in the timelines she chose to not have a relationship with them. For this reason as well, I really didn't care much for that ending and it didn't make sense either how they managed all to be reincarnated into the same thing considering they were only given one option every time? Works for cute effect I guess.

Music is fine, they clearly played with the nostalgia trip in that aspect a lot. But it felt like they wanted to precisely get some easy points for doing that. I recognised many of the songs and brought me back in time, but sorry, it's not enough to make this show good, I'll rather just go and listen to the music without watching this.