Not gonna lie i feel like this is kind of sloppily written, a lot of things happen with no foreshadowing, like nike saying that at the end feels really out of place. Also overall the dark pieta probably representing her more negative thoughts is cliche as fuck and doesn't really delve too deep into the actual psyche of the character.
Also Chiaro's just randomly kind of guessing the clock thing is extremely weird, if you just suddenly learnt that you started repeating days why the fuck would you think that there was some sort of limit to it. I mean this is a minor grip because it's understandable to hypothise that there will be something happening when it hits 1200, since that's when the clock goes back to zero. But why would you assume that that is the limit, after all clocks just normally go around in a loop anyway.
I might be wrong about something, maybe it gets explained better over time, but i just think the writing feels bit shitty partially. It's like what some edgy high schooler would write as a story almost. Characters are alright though, apart from the alt pieta which has had like no character developement so far, but the main three are quite nice.
The manga does have potential even after all those shittier moments, I can see that there is a bigger overarching plot, that is actually quite interesting. It's just there's a lot of empty metaphors and useless symbolism that is very loosely connected together, I just hate this kind of writing where everything is seemingly symbolic. Symbolism alone doesnt make something good or deep, it's a trick to disguise the fact that you have nothing actually philosophical to say about the things, just bunch of empty words with no meaning.
Still a solid 7/10 so far, mostly because of the overaching plot, art and the characters.