For me, the best chapter is Vann. We learn Fuuta's past reincarnation as a fallen knight. I immediately feel sad to Vann. As a fallen knight, with no hope, he finds best friends, even a daughter whom he loves dearly. I feel bad for him, but also feel glad when his deranged brother died in a jest way (Vann dies in a jest way too, btw... what a shame... but at least, he dies happy.)

Through his pasts, we learn a lot about him and his friends. How he makes friends, how he has the mark on his left cheek, how Kouko hates him, how his friends behave why they are still entangled with each other, and many more. The character developments here is great, can't believe his Hoshi no Samidare is a shit. I honestly can't believe it's from the same mangaka. Well, the art is still not my taste, but mangaka is improving (with the writing). Each of every Fuuta's pasts make me sad and leave me with frustration.
Vann is the saddest one IMO, his friends died one by one, yet he still pretended to be tough, but deep down inside his heart, he felt lonely. Until he found Rei, he learned how to be "sober". The end of his life is a bit funny, but also sad. His life was thrown away just like that. Feel bad for him, but also good for him. At least, he's having fun.

Now, for the most depressing one is Lafalle arc. How is Lafalle the harbinger? I don't think he's wrong when he pulled all the plug of those machine that kept the brains alive. I believe in reincarnation, so I agree with Lafalle's theory. When you "alive", your soul is still with you. They can't go to the "place" to reincarnated. But I do think this is the plot hole: maybe people just don't want to make babies anymore? So, there's no body to be attached with the soul. As he mentions in the early arc, super humans don't want kids, maybe non-super humans don't want kids either, seeing how desperate their world have become?

In Fortuna's arc, there's again another plot hole. Fortuna said that the spirit circle and East are a set, but Koko just take off the spirit circle and use it ever since with her own. Then, the spirit scholars who East and Koko found made artificials spirit beasts. So, it's ok if it's animal spirits as long as it's not the human spirits when it's taboo? Flambe, the one who suggested it, took his own life after this. Then one spirit scholar said it's actually not taboo? WTF? Which one? So, Flambe's death is a vain? Fortuna's arc has lots of plot holes. Like he waited for Fuuta in some "dimension" to talk to him? How? If when Fortuna takes over Fuuuta's body is a personality, then it's fine. It's like you have multiple personalities disorder thing, but to have a soul un-reincarnated BECAUSE he wants to talk to himself? Dude... you need to reconsider it. How come Fuuta be born if the soul hasn't departed yet? It's not a bad arc, but it's a conclusion of all of the reincarnation, so it should be done with a great detail to close the curtain of this mystery.

Mangaka likes to make serious storyline but kinda trap in his own story and mind (like Tetsuya Nomura's galaxy mind, but at least, his art is great). And his ending/conclusion is still not good. Instead, it left with new questions: who are those 4 people in the first page near the end? Are they Gods and Goddesses who govern worlds? Who is whose father? (As one of the god said it to Spacifica). Who is Spacifica actually? A servant to those Gods? Why Spacifica appeared in Lafalle's arc? For what purpose? Just to choose a new manager? Perhaps, he chose the manager so someday someone like Lafelle can freed the souls? How the world created again after the destruction in Lafelle's arc? Fuuko seems to have the answer, but her arc is just a chapter. Who are those aliens? They are aliens, but with their conversation, they seem are cosplaying as aliens? In my faith, we learn that when the earth is destroyed, a new earth will be created and a new "God" (we actullay don't call Him God, but I don't want to said it so specificly) will be reborn. There are many many worlds in many many dimensions as well (as the four Gods presented to the readers). As long as there's "karma" in that earth of that dimension still exist, they (the earth and other living beings) will be reborn again, until each one of us can let it go. I see the mangaka probably has a certain faith like mine, so I kinda can absorb it without any question, but what about to those people who zero knowledge of this certain faith? They will be left confused. And as a mangaka/writer, it's your duty to make them enjoy your creation without any confusion.

As someone who believe in reincarnation, I can say that this manga is taking it pretty well. We have "debts" to our previous lives’ friends, that's why we still meet them in the current live. We will keep meeting until we or them pay off their "debts". Notice how the mark on Fuuta's cheek is fading away little by little in each past? It symoblize their (Fuuta and Kouko's) hatred. It's completly faded in the end of the series indicated they already break the circle of their hatred.