|Age||10 (Original Past) 26 Fixed Future|
|Magic||Flying through the sky|
She was found many years before the beginning of the series, found on a river by an elderly couple who raised her in their cabin in the forest. Yakumo trained Nikaido in martial arts since she was 4 years old, going so far that the little Nikaido was able to do highly complex acrobatics and broke wood plates with no effort, (but showing wounds of the harsh train).
She shown feelings towards Asu, know as Kawajiri at the time, and was saddened by the fact he was chosen to take the Devil exam, knowing they would no longer see each other or be able to reciprocate her feelings.
When Nikaido, still a small child started to use her magic for first time, accidentally time traveled to the past and accidentally distracted the elderly couple wich would in the future become their parents, Nikaido, not understanding why Yakumo wasn't there, quickly understood the situation and ran away from their home to the river, but was too late, the baby Yakumo drown in the river and her body was buried near with a tombstone with the epitaph "An unnamed soul rest in here" horroryzed, Nikaido unsuccessful tried over and over to go back to the past and fix what happened, but every time she drifted everyone she loved away. The experience traumatized her and with the help of the newly ascended Asu. Nikaido started a new life alone in Hole.
After Nikaido decided to practice once again her magic to be able to do things right and save Yakumo, she created a magic time machine out of smoke. Together with Asu, went back in time and found the baby Yakumo in the river, but the elderly couple wasnt near the place thanks to previous interferences of Nikaido (thanks to her time travel, they haven't even raised Asu, so they were all alone) the baby used her magic for the first time when she was scared by the two time travelers, flying through the sky until she fell with the couple, Asu and Nikaido thought that, just with a little interference, Yakumo was able to forge her own destiny by flying to her parents, who raised her as their only daughter.
When the two went back to the future, they saw a grown up Yakumo flying through the sky, by that time, she would had 26 years old, realized she finally overcome the burden, Nikaido told Asu to teleport them back to his house.
- Thanks to the fix Nikaido did in order to saver her life, she grown up without knowing neither Kawajiri nor Nikaido, as the first was already an orphan raised in the Devil Church and thanks to Nikaido's magic only one iteration of her could exist at the time, so she was never found by her adoptive parent in that timeline.