D-D-Don't drop Labrys just yet! (For the sake of Labrys players...)
The key to winning agaisnt Yu is patience.
When being pressured in a corner, the best thing you can do is just block. But a lot of Narukami players need to go in the air at some point; I usually wait until that happens, then launch a 2B. Chances are you'll get a counter hit too, so follow up with 5D (x2) & do whatever you please from there.
However, good Narukami players will use a more ground based pressure, in which he only has 1 split-second opening (you'll start to notice this when he starts finishing his combos with his persona, or when he back-dashes away from you). In this tight opening, 2AB usally does the trick 'cause it's fast, hits low & covers a lot of ground. Sometimes, you're able to 5B instead (it has more reach than you think!).
Yu mid-screen is much easier. He'll try to close in on you with his thunderball stuff, so be careful.
If you time it right, use your chain knuckle (the SB version makes you invincible to projectiles).
If he jumps to do a thunderball, run straight up to him & launch 2B (use with caution mind you).
If he starts respecting you, throw out some orbs & slowly close in on him.
Yu might be a bit tough, but he's manageable.