Yukiko does have an answer to jump B. Its 5A and I just tested it right now. At worst it clashes but because you are grounded you can gatling 5A again while Lab is gets hit with a counter hit.
Maybe if the Labrys player jumps right in front of you, which they never do. It's usually a smack in the side of the head with the axe. The blockstun and hitstun is so insanely high she can confirm from anywhere.
Anyway like I said, I'm not going to pick a match where I can either get 300 damage for making the correct anti-air of lose 50% of my life against Sentinel. It's time to move to a character that can stop cheese before it gets started. At least no one can claim Mitsuru is weak.
The only part that sucks about this is starting from square one with combos. I knew I should have listened to my gut when I bought the game.