That's just fictionally high skill level boi. It's not PIS. Being impossible by normal means doesn't mean it's impossible in fiction, let's call hax and AP PIS too. It is stupidly high skill level, not "the plot favouring him" he can do all of that he doesn't get saved cus "lol plot" he gets saved by his own skill which is just stupidly high cus he trained hard. The plot never bent in his favour cus it's not giving him shit outta the blue, he could always do all of that, due to being skilled, so other that "creating" the character the plot was never present.
Yes because everyone besides him has some form of talent and just cus it's not "in norm" doesn't mean its PIS. Obviously it's not the usual norm, otherwise it would be skill vs skill and talent. But characters like
Edelweiss can theoretically do the same heart restarting technique. And characters like
Shizuku Kurogane has so much magic skill that while the best
Stella Vermillio (a prodigy that is said to appear only once in 30 years) can do is bring out a lot of fire, Shizuku can reform her body on a celular level to completely change what the body is made of. While in terms of swordsmanship no one other than Edelweiss can match him (yes edelweiss can match him in skill), there are a lot of others who can do rather good feats of their own like Dandallion, Shizuku, hell even
Ouma Kurogane has stupid feats though mostly related to evolution rather than skill. And beating probability is just him having really good muscle memory, notice how if you're too good at a certain game, you don't need to think, but rather your body just does stuff on it's own? Yeah, ikki's level of muscle memory is the same thing, even if he messes up it'll just autocorrect itself due to the very good muscle memory, same for slipping, missing, and everything the probability was making him do.
Yes the AI is believable, why would it not be? Breaking immersion doesn't mean "lol PIS", it just means the reader cannot fully relate, but that's subjective. "The plots bends to his favor" care to mention a few cases?
"The plot makes ikki overcome everything for the sake of the plot". I mean technically, every AP, hax, skill, mechanics, story, characters everything is technically plot, so pre-stated skill overcoming a character is technically plot overcoming the character right? Dude drop it, it's becoming cyclic at this point. You are calling something "PIS" with nothing to back it up other than "it's too good". Yeah it's too good, doesn't mean "the plot is going in his favour" but when the story was created for plot reasons he was chosen to have really good skill, same as how characters were chosen to be really durable, really strong, really haxy etc. The plot decided all of that when the show started, that doesn't mean PIS though.