Ball Breaker (4) (ボール・ブレイカー その④ Bōru Bureikā Sono 4), originally Lesson 5 (2) (LESSON5② Ressun Go 2) in the UJ release, is the eight hundred thirty-eighth chapter of the JoJo's Bizarre Adventure manga. It is also the eighty-sixth chapter of Steel Ball Run.
Johnny takes a moment to silently thank Gyro for everything he's done, and shoots. Valentine orders D4C to hide inside the light, but when the nail bullet collides with the gap in space, Valentine and his Stand are overwhelmed by rotational energy. Tusk ACT4 forces the dimensional wall open and invades the gap in space, and proceeds to pummels D4C and Valentine violently into the ground, creating a spherical crater in the process. However, Valentine uses his coat and disappears into another world.
Due to having hopped from the bottom of a crater, he finds himself being underground and sends D4C to this world's Valentine. Valentine then decides to go back to the "Root world" before Johnny's nails grow back and finish him off. Suddenly, his foot turns on itself he turns to see D4C spinning around before heading through its original location underground, dragging a hapless Valentine with it. Valentine doesn't understand why D4C is going back to its original location and suffocates.
He decides to hop into another dimension and sends D4C to that universe's Valentine. D4C is again going underground with Valentine. Valentine dimension-hops again and tells his counterpart to quickly go kill Johnny, but D4C's drags that Valentine underground too. The damage Tusk inflicted to D4C is following it.