Interesting deck!!!
I agree you need more win cons, all i see right now is quietus spike. If you want a budget tutor for quietus spike then Drift of Phantasms will work for you. Lots of artifact tutors in blue too if you want.
Mask of Memory seems playable here too.
Ideas unbound is a cool card. If you ran Teferi's Ageless Insight then i would keep it in. Otherwise i would lean towards Impulse .
Cloud of Faeries seems playable here, as does Coastal Piracy or Reconnaissance Mission .
Looking at your mana base, High Tide seems playable. I might run Temple of the False God or Rogue's Passage , or even War Room if you are interested in some nonbasic lands. And Mystic Sanctuary is sweet, i would add that. Also, add Sol Ring !
Lots of alternatives for cancel, i would run a cmc2 card from your maybeboard. But if you want to stick with cmc3 counterspells, i like Void Shatter , Dissipate , and Dream Fracture .
Anyway those are just some thoughts, cheers and have fun!!!

Bomb suggestions I appreciate it!

Draining Whelk and Hypnotic Sprite become reusable counter spells. They have flying so you can usually Ninjitsu off of them. Faerie Duelist is useful.

If you run out of Ninjas Feldon's Cane or something to refill your library could help.

Higure could do some serious commander damage with Octopus Umbra

Oh, one more. Pilgrim's Eye

Higure is cool but maybe Tetsuko Umezawa, Fugitive would be better at the helm?

I’m trying to really make ninjitsu the mechanic by taking advantage of ETB and evasion simultaneously. I do think Tetsuko is a better commander generally, but Higure is perhaps my favorite card in terms of flavor, so I’m trying to feature him with this deck

This is really cool! I love that you stuck to your guns and kept Higure - I think it adds a ton of character and uniqueness to your deck :)

A card I absolutely love and don't see anyone use is Wu Scout . It might be a good fit here in your deck! It could help trigger your nigitsu with pseudo-unblockable and also be an interesting etb to recast as you look at multiple hands across the game.

I like this! I’ll be sure to add it.

Love this! I love seeing lesser used commanders.

Thoughts on Cunning Evasion ? Or adding a few nonbasic lands like Myriad Landscape , War Room and Castle Vantress ?

So I added Grazilaxx, Illithid Scholar for the same kind of effect as Cunning Evasion , because for this deck it’s important to try to put any effect I want in the deck on a creature instead of any other kind of permanent. That way it can potentially combo with ninjas, be tutored out by Higure, be played repeatedly, help me swing for damage. Our card advantage also comes from damage often, so my T2 play needs to be something that will feed that engine, rather than an enchantment that only really helps ninjas in combat.

Somehow I don’t think I’ve actually EVER seen Myriad Landscape before, but it is a rather striahgtforward ramp card correct? With only one color mana to worry about and how cheap the card is, I might just put that in! Thanks!

The War Room would be cool for ALL of my EDH decks, which are all mono colored, but the budget is a little limiting. Hopefully one day. Anyways thanks for all the suggestions! KBK7101