Black Moon: Chains of Time

In the thirtieth century, Crystal Tokyo is dying. The sky has gone black, the city stands frozen in pale stone, and the Queen who held it all together sleeps sealed in crystal with her eyes still open. A small girl fell out of that ruin and back through a thousand years, clutching the one thing she stole and the certainty that she caused all of it. She lands in a sunlit park, at the feet of a teenage crybaby with impossible hair who has no idea, yet, that she is anyone's mother.

This is the Black Moon arc told from everywhere the manga never looked.

It belongs to Mamoru, who has started dreaming of a future he cannot reach and cannot stop, who meets a hostile, frightened child and feels something older and worse than recognition. To the four guardians, hunted and taken one by one, each cut from the others and left to hold the line alone. To Setsuna, who has kept the loneliest post in the universe since before any of them drew breath, and to the little girl who calls her Puu. And to the Black Moon itself: a beautiful, ruined prince who wants the woman at the center of everything, the brother who would set fire to the world to keep him, and the patient hooded thing behind them both, who understands that the only weapon that has ever mattered is a child convinced she was never loved.

They are all circling the same bright, oblivious girl. Not one of them can save the future alone. And the future, in the end, does not turn on the Silver Crystal at all. It turns on whether one furious, grieving, nine-hundred-year-old child can be loved enough to keep, before the dark reaches her first.