I am bored so I drew how Mito would probably look like in this life cycle. I mean let's go. It's not accurate but atleast near.

Baby Mito
Age: 6 months

Kid Mito
Age: 4 years

Genin Mito
Age: 8 years
Chunin exams
Squad 7
Mito got killed in the last of sasuke and Naruto battle. But that time he wasn't genin. He was promoted to chunin. In the last so I put his status on genin in this.

Chunin Mito
Age: 13
Danki traning
Ink mark awakening

Jonin Mito / Naruto the last
Age: 16 years
The last of the Naruto anime

Mito the last.
Mito in Boruto
Age: 27
God of creation.
Multiverse Guardian / protector

So hear me out

After Mito was dead for 4 days in the battle of Naruto and Sasuke. He somehow got to life. After that Danki the younger brother of Danzo picked up Mito for training. But the real intention of Danki was to make Mito strong and take over his body then defeat Danzo and take over His body.

But over time from the training with Danki , Mito didn't tear his soul apart to gain Ink powers. Instead he developed his soul like that, that he do have a soul but he can use advance Ink powers. But due to that his hair colour changed to black.

Plus Mito got Ink curse marking on his cheeks.
That's all for it.