As he's squatting there playing with the grappling hook, a greasy hand rises up out of the water and grabs his wrist. Another hand gropes for Hiro's other hand and grabs the sword instead. Hiro yanks the weapon free, feeling it do damage, and shoves the wakizashi point first into the place between those two hands just as someone is sinking his teeth into Hiro's crotch. But Hiro's crotch is protected—the motorcycle outfit has a hard plastic cup—and so this human shark just gets a mouthful of bullet-proof fabric. Then his grip loosens, and he falls into the sea. Hiro releases the grappling hook and drops it in with him.