Splinters POV
I was wandering the sewers with my boys looking for the source of a noise that scared us during the night. Until we stumble upon a small child who was about 6 years old abandoned. I quickly picked it up and took him to the subway we live in.
The next morning I wake up to see the boys trying to communicate with him. I learned about him what his name is, if he had parents, His name is izuku. I used my observation haki to sense his mother. I see a woman in Japan she looks like she has no idea he's missing.
She looks like izuku and apparently he has a sister with a powerful quirk. I will rase him until he is 18 then i can take him home.
About 4 years later I was training all of my boys and I decided to let them spar. While sparing I see izuku is having a hard time defending against all the others. I can tell the boys sees it also.
Turtles POV
Leo: what do we do against izuku we have shells that can protect us but he doesn't
Donnie: I know since he's human he doesn't have any way to protect from attacks besides his weapon
Raph: he needs his own turtle shell
Leo: but how?
Mickey: let's make one
Donnie: it should work plus he can carry his weapons in it to
Izuku: whatcha talking about
All: AHH! nothing
No one POV
They all split up to look for stuff to make a shell. They also tell master splinter who agrees with it and decides to train izuku more so they can keep looking without having to worry about him finding out.
It took 3 weeks but they made a shell as tough as theirs. They waited for Izuku's birthday which is the next day to give it to him. Apparently they found a way to make carbon fibre and made a backpack out of it.
