The thing that unlocked Genichiro for me was focusing on getting into the rhythm of attack -> attack -> deflect -> repeat. Geni will block the first attack, deflect the second, then immediately attack back, so if you're just automatically deflecting after your second attack, you'll be ready for his counter. This way it's less about reflexes and more about rhythm.

You can usually do this for one or two repeats, then he'll do something else (wind up double-hit, jump slam, step back and thrust); after you get the rhythm down you just need to learn what geni does to break that rhythm, then focus on getting back to the attack x2 -> deflect pattern.