Akihiko takes a defensive stance, and throughout the active frames, he'll counter mids or highs, with each version having their own followups. Has a lengthy amount of recovery, so you'll want to be careful with using this. Both the A and B version lose to lows, so don't throw this out amid your pressure strings unless you're, say, fighting Adachi or something. Counts as a Cyclone move.
The A version will lead into the A version of Corkscrew Punch upon countering a move. This counts as a cancel, so it'll increase the Cyclone level.
The B version and the SB version can both cancel into any Cyclone move, but if you choose to do nothing, Akihiko will instead use the parry to give a thumbs-up and gain SP. Fully invincible during the animation. At Levels 1 through 5 for the B version, Akihiko will gain 15, 30, 45, 45, and 70 SP.
The SB version is the best for countering, as it can counter lows. It's functionally the same as the B version otherwise. At levels 1 through 5, Akihiko will gain 40, 55, 70, 70, and 100 SP! Impressive amounts, until you realize you need to spend 25 SP to activate this, so you're really only getting a net gain of 5 SP at max.
The B and SB versions share a weakness, however; they're generally weak to mashing, even upon parry. Not only is the recovery vulnerable should you choose to go for the SP parry, but they offer no invincibility to your followups. As such, you can successfully parry an attack, gain SP, and get counterhit by your opponent's mashing. The A version doesn't share this weakness, however, as the Corkscrew Punch is very swift; the same is true if you choose to forgo the parry for the B and SB versions for an A Corkscrew Punch only. Because of this, you should only really use the B or SB versions when against an option an opponent has to commit to, such as a DP or Burst for the B version, or an option like Yu's Swift Strike for the SB version. Try not to parry a DP or committal low if they have the meter to One More Cancel, as they're still technically treated as hitting you and can thus One More Cancel their attack to hit you again.