Board Thread:Naruto Gaiden/@comment-4271790-20150520184250/@comment-3531945-20150520210529

Mecha Naruto wrote: What is Shin's Mangekyou power, is he doubling Kunai (or whatever that is) like four Kunai to eight? FF-Suzaku wrote: It appears that he's using it to control his chain-shuriken weapon. He activates it, focuses his eyes on it, then the four blades seperate from the base and split into eight blades total, which fly at Naruto and the kids.

So, some sort of telekinesis, I guess. Yeah, i believe sasuke did something similar with his sharingan during his first battle against orochimaru