It works. You can hit Bang. I just tested it.
For a split second after the super flash, Hakumen turns around and faces Bang. If you input Hotaru in that moment, you can hit him.
But it requires strict timing; otherwise it just whiffs. But either way you're safe.
Actually I just figured out an easy way to time it: watch Bang. The moment he vanishes, input Hotaru. By the time he reappears, he will get hit.
And if he does it when you're on the ground, you can Renka him out of it.