Help define Hatsu?
I decided to try to define ability from Gintama - ability that Kagura had post-timeskip.
It allowed her to seemingly change ages between a little kid, her actual age (15/16-ish teenager) and an old granny.
I assume that the ability would have two parts:
- self-regeneration - using enhancenent abilities to speed up regeneration at caloric cost it would take normally, but at once
- changing age she regenerated toward - using transmutation or manipulation - but I have no idea what would be limitation/cost here
Kagura would probably initially create this ability as memento to her mother, who was an immortal, but then add age-shifting part for convinience + pranking people.
Possible restriction I think Kagura could agree that her nen cannot directly affect other people - she could use it to defend herself (durability and healing, avoidance and such) or indirect attacks.
She can use nen on her umbrella to be better at causing a gust of wind and use that to hit enemy, but she can use only her (Yato) strength for attacks.
But for that she would be better at using nen on herself and tools she considers as hers.