Aside if it can be resisted or not it's just clearly bugged and even when you apply it this acupuncture that is supposed to last 2 rounds falls off a lot of the time for some reason next round. Idk is it coded as irremovable only for round when you apply it then it swaps to basic acupuncture and because of it falls off vs immune characters or wtf is going on with it.

Shisui is one big mess bugs and balance wise. Shame Tencent destroyed the game with addition of this ninja since from now on we will be getting beyond broken things that make no sense to compete with this cancer. 10 standard attacks, 4 mystery ninjas whats next at this point

1) Y mystery is 100% bugged and 2 round acupuncture simply doesn't work - enemy can mystery most of the time next round

2) Standard debuff is completly loco preventing your own team from applying debuffs and ton of other random bs happening with it

3) Animation not changed after the patch to his abilities

Said it already 10 times, it's simple false advertising if ninja doesn't do what he is supposed to do and it's illegal so things like that have to be fixed and doesn't matter balance wise.

Offtopic below:

I will never understand hype about anime Shisui. People make him sound like he was a god tier ninja, same tier as idk let's say Pain meanwhile in reality he was not that strong at all and lost to Danzo + bunch of useless ANBU members (yes useless... ANBU members couldn't even defeat 1 summoning from Pain).

Outside of Kotoamatsukami which could be stopped and spotted pretty fast by other teammates so outside of duel 1v1 fight pretty much meh ability. (5 kage summit perfect example how they stopped Mifune from being controlled or how Danzo wanted to defeat Sasuke before trying to control Obito since he knew that if he did it earlier Sasuke would prob just break out Obito from genjutsu and gg since it has crazy cooldown) he had nothing special offensive/defensive jutsu wise. If he was as strong as people make him to be he would use Susanoo (kishimoto himself never confirmed he had one, just video games use this version) instantly obliterate ANBU members and use Kotoamatsukami to control Danzo - gg but nope he was not that strong and lost.

Not to mention teen / young adult Obito had same tier genjutsu with basic sharingan mind controling perfect jinchuriki Yagura so i really don't get the hype about Shisui, whatever ninja that had amazing personality BUT was weaker or about the same tier as Danzo and akatsuki members like Deidara / Kakuzu and that's it.