[The following is a tentative blurb. Screenshot saved on Weibo.]
During a voyage across the starry sea, the spaceship of Yato Kamihiruma Shinjo is caught in a temporal rift, and all the controls fail at once.
The ship suffers severe damage and emits a blaring danger alert. For her own safety, Shinjo climbs into the emergency cryogenic sleep pod.
When she wakes again, she finds herself face-to-face with a red-haired boy.
His skin is pale, and the long red fringe over his forehead covers half his face. The one visible eye looks like the cross-section of an onion, with layer upon layer of rings.
Shinjo soon discovers that the hatch on the ceiling of her ship connects to the wardrobe in the red-haired boy's room.
Caught in the temporal rift, her ship is wedged between the seams of time and space. Time has stopped, throwing space into disarray and causing the hatch on the ship's ceiling to overlap with the wardrobe door on an unknown planet.
One door is all that separates the two spaces, allowing travel between them.
To repair her ship, the Yato makes a pact with the boy named "Nagato" and joins an organization called "Akatsuki"...
PS:
1. Probably a medium-length story of no more than 200,000 characters. Pairing: Nagato.
2. The original timeline is a little messy, so I've sorted it out roughly. Ages in this story: Nagato is four years older than Obito, two years older than Yahiko, and one year older than Konan.
3. Background: Nagato meets Yahiko and Konan at age six, becomes Jiraiya's student at seven and studies for three years. The three of them establish "Akatsuki" when he's eleven, and the Third Shinobi World War begins when he's fourteen. When the heroine and Nagato first meet, they're both twelve.
Theme: The butterfly effect.