A tactic, not a recorded winning move
A henka is a sudden sidestep at the tachiai. Instead of meeting the charge head-on, the wrestler moves off the direct line and may guide, slap, or pull the opponent past.
Henka is legal, but it is not itself an official kimarite. The recorded result describes the action that actually caused the loss, often hatakikomi or hikiotoshi. A wrestler can also attempt a henka and still lose if the opponent keeps balance and adjusts.
The tactic is debated because it can end an anticipated matchup almost immediately. That reaction is strongest when an upper-ranked wrestler uses it, but legality and audience approval are separate questions.