Wow the counter in Rain Blood Chronicles is kinda ridiculous. It has very lenient timing, does 9999 to jobber enemies, which I assume will be one hit kill for the rest of the game, hits enemies with ranged attacks, boosts your score rating significantly and seems to hit more than just the enemy that was attacking. That said, it doesn't do that much on bosses with a health bar, but it still does a decent amount of damage usually knocks them down. That's not enough so that the optimal strategy is to just wait and counter everything but it does seem pretty viable to do that.
I only played the first stage and got a terribad score rating, partially because I was testing out stuff (you can dash cancel any move, at any time (I think) with one of the characters, which also seems kinda weird), but mostly because I suck. I was kinda down on the game because the animation/attacking is kinda janky but that first (real) boss was interesting enough that I want to continue to at least see the rest of the enemies and use more of the Kee Sword user. It does seem like the kind of game where the challenge comes getting high ranks instead of just completing it.