Chapter 23

Ripple Overdrive (1), originally Northern Wind and Vikings in the WSJ release, is the twenty-third chapter of the JoJo's Bizarre Adventure manga. It is also the twenty-third chapter of Phantom Blood.

Summary
Zeppeli tells Jonathan that the only way to beat a vampire -- or a zombie, in this case -- is to destroy their brain completely. Jack the Ripper, still alive, grabs onto the sword embedded in the tunnel's ceiling. He pulls it down, revealing a secret passage that he then runs into. Speedwagon is put off by the prospect of entering the passage, but Zeppeli insists that they must follow Jack. Zeppeli tosses his full wine glass to Jonathan, and says that only Jonathan will be going after him. Zeppeli then tells Jonathan of an old saying that originated in Norway: “The Northern Wind Made the Vikings”

Zeppeli tells Jonathan that he must defeat Jack the Ripper in the secret tunnel without spilling a drop of the wine, or Zeppeli will abandon Jonathan on his quest, regardless of whether he defeats Jack or not. Speedwagon objects to the ridiculous challenge, but Jonathan, following the old Norwegian phrase, enters the secret passage.

Zeppeli then tells Speedwagon the story of a Caribbean fisherman he had once met. One day while he was out at sea, his boat was attacked by a giant shark that had plagued the waters for some time. His boat was destroyed and his foot caught in the wreckage. In a bold move, he severed his own leg with his fishing spear and used the wound to bait the creature. The fisherman was able to kill the shark and became the hero of his village. Speedwagon asks Zeppeli if Jonathan will be able to finish his challenge. Zeppeli replies that if Jonathan fails, he would not be able to defeat Dio.

Jonathan searches the maze-like passage with a torch. Unfortunately, because of the structure of the passage, some places are too dark to see, torch or not. Nearly too late, Jojo realizes that the torch makes him an easy target, and the zombie ambushes him with a torture device shaped like a giant rib-cage. Jonathan barely manages to escape the trap, but not without receiving several cuts along his arm and nearly spilling the wine. Jack the Ripper vanishes into the darkness. He extinguishes the torch in an attempt to avoid giving away his position again. However, he quickly realizes that, without the light, he cannot tell where Jack is hiding, either. Though he attempts to conceal his presence, Jack is already aware of Jonathan's position due to the smell of blood coming from his cuts. Unknowingly, Jonathan is walking towards another ambush.

Jonathan is about to round the corner when he notices a ripple in the wine he's holding. Jonathan realizes that this is the reason Zeppeli gave him the glass. The wine acts a Ripple detector that can be used to sense life around him and pinpoint the zombie's location. Jonathan uses the Sendo Ripple Overdrive technique to attack Jack through the wall. The Ripple connects with Jack the Ripper's head and kills him completely.

Back at the entrance to the passage, Zeppeli and Speedwagon hear the cry of the dying zombie. Zeppeli remarks that Jonathan must have figured out what the wine was for and that the "North Wind" appeared to have made a "Viking" out of him after all.