These are probably old, but I was messing around in training mode to see what there is to do after Yukikaze. Some things I did:
(midscreen)Yukikaze, 623AA, j.2C, airdash, j.C - 4559 damage (6 bars)
(corner)Yukikaze, 623AA, j.2C, airdash, j.2C, j.2C, j.C - 4811 damage (6 bars)
(midscreen)Yukikaze, 236A, 623AA, j.2C, airdash, j.C - 4654 damage (7 bars)
(corner) Yukikaze, 236A, 623AA, j.2C, airdash, j.2C, j.2C, j.C - 4879 damage (7 bars)
(midcsreen)Yukikaze, 236A, fully charged 6C - 4531 damage(5 bars)
(midscreen)Yukikaze, 236A, dash, 5B, j.B, j.C - 4558 damage(5 bars)
(midscreen) Yukikaze, 236A, dash, 5B, j.B, j.C, 214B, j.C - 5010 damage(7 bars)
(midscreen)Yukikaze, 236A, dash, 5B, j.B, j.C, 214C - 5003 damage(8 bars)
All combos done on Ragna. 214A and 236AA don't seem to connect when too close to the corner.
Oddly enough, if you input the move too soon, Hakumen will move to the other side of the opponent with the slash part of the counter but it will be canceled into your move(doing no damage) and net a counter hit. Maybe there could be a use for that in Mugen, but I don't see why you would forfeit the super damage for a counter hit.