Naruto: Who made him a ninja?

The 52nd year of Konoha.

The Third War ended, the Fourth Hokage and his wife passed away, and Orochimaru also left Konoha.

And the boy who was brought into the Root by Danzo when Kabuto Yakushi "recommended himself" fell into deep thought when he looked at his systematized task.

.......

A few years later, I don't know how many people roared: Who is it? Who let him be a ninja? !