WARNING: The following contains spoilers for One Piece Chapter #1018, "Jimbei vs. Who's-Who," by Eiichiro Oda, available in English via Manga Plus and Viz Media.
One Piece's last chapter, #1017, unveiled a shocking revelation about the Tobiroppo, Who's Who, and his connection to Luffy's Gum-Gum Fruit as he faced down the Straw Hats' newest member. Expectations for an exciting follow-up to this fight between Who's Who and Jimbei began to skyrocket, and luckily, #1018 does indeed deliver a frightful blow from our favorite reliable Fishman.
As the fight resumes, we see just how terrifying Who's Who power truly is, with his fang pistol even able to burst the floor and hit the pirates skirmishing beneath them. Jimbei dodges in time, which is a surprise for Who's Who as he did not expect a Fishman to move so quickly on land. The hard-boiled Jimbei, however, has had enough of ignorant stereotypes, remarking: "Don't you know casual racism against Fishmen is out of style these days?"
Who's Who dashes forward to bite at Jimbei. The martial artist blocks it with his armament haki-coated forearm, but the force is still strong enough to push Jimbei back. Jimbei then uses that force to toss Who's Who overhead with his Fishman jiujitsu. The helmsman tries his water shot, but Who's Who uses Shave to dodge out of the way at the last minute.
As the Sabertooth Tiger Devil Fruit hybrid catches his breath, he asks Jimbei about a story he heard from a guard in Impel Down. The guard told him of the Sun God, Nika, a figure that slaves in the past would pray to in hope that the legendary warrior would free them. After so much torture and misery, Who's Who was eventually swayed by this legend and prayed to Nika too. So now, Who's Who asks Jimbei, given his former status as captain of the Sun Pirates and the slavery associated with the history of Fishman, if he knows anything more about the story of Nika.
The disgust on Jimbei's face reveals just how insulted he is by the former assassin's ignorant question, but Who's Who doesn't let up physically, unleashing a barrage of finger pistols on the Fishman. Jimbei has to resort to encasing his body in Armament Haki to protect himself. Who's Who then says that same prison guard disappeared a short while later and worried for his own safety, he decided to plan his escape.
The most shocking moment of the fight comes when Who's Who's finger bends under Jimbei's haki-reinforced skin. The Straw Hat helmsman has nothing to say to Who's Who, so he grips the Sabertooth's wrists to headbutt him. Even Who's Who's fang pistol can't break through the rage that Jimbei is feeling, and when he tries to escape, the Fishman steps down on the tiger's tail. Jimbei ends things with a very powerful Demon Brick Fist to Who's Who's face, accompanied by the badass line, "If you're going to run your mouth about history, be ready for what you're stepping into."
Jimbei joining the Straw Hats has been teased as far back as the Fishman Island arc in One Piece. To finally see him here in Onigashima facing off against such a spiteful man who holds nothing but contempt for Luffy is such a brilliant way to illustrate how committed the former warlord is to seeing Luffy become the Pirate King. In addition, series creator Eiichiro Oda also seems to be setting something up for the future by introducing Nika, the Sun God. What that may be we can only theorize about for now.