The Rengokureiha (literally Refining Hell Spirit Blast) is one of Thin Nen's special techniques. It is notably different from other special attacks in that it requires both punch buttons be pressed in order to execute the technique. First, Thin Nen forms a ball of energy in his hands for a second, then he unleashes the energy in the form of a skull-shaped projectile that flies at the opponent. The ball of energy forming in his hands can provide him with some defense against attackers, as it's capable of damaging anyone who gets too close to it, as well as destroying any projectile attacks thrown at him. The attack, however, can be interrupted by low attacks or projectiles that travel low along the ground.
Since Power Instinct 2, Thin Nen has gained the ability to use the move in the air, with the difference that it hangs in place, and was called the Kuuchuu Rengokureiha (Aerial Refining Hell Spirit Blast). Both moves changed in Power Instinct Matrimelee, where only one punch button had to be pressed to use the technique, and both would change accordingly depending on the strength button pressed.