After using Violet's Clairvoyance ability under the Asura form, El quickly found Vander Decken IX's hiding place somewhere in the deepsea.
As the Mark-Mark Fruit ability needs to touch the target in order to mark, the time he secretly touches Shirahoshi is when Queen Otohime was assassinated and the palm that touched her has never been washed since that time.
In order to forcibly marry Shirahoshi, Vander Decken IX has offended the entire Ryugu Kingdom by sending a love letter in the form of weapons with his devil fruit ability, because of this Shirahoshi can't even attend the funeral of her mother, so, everyone, including El, could not wait to peel off his skin.
Vander Decken IX's skin obviously knew how much he was hated, so not long after he sent his first love letter, he had already escaped from Fishman Island and hid somewhere in the deepsea that even Jinbe who was one of the Seven Warlords of the Sea, could not find his hiding place.
However, as a devil fruit user, even if Vander Decken IX's fishmen, he can't be in contact with seawater as it will make him powerless and nullify his mark at Shirahoshi.
So he can only wrap his whole body with Bubbly Coral, and to prevent any sharp objects from it while walking in the dark, he must always carry a lamp with him.
This faint light source from the lamp is the reason why El can successfully find his hiding place, then in the next second, El directly flew out of the window, and use Razor (Kamisori) which is a combination of Moonwalk (Geppo) and Shave (Soru), to turn into an afterimage and leave the Fishman islands.
Before their figure passed through the protective film, Carina controlled her arm to take out a Bubbly Coral and squeezed a giant bubble that wrap them while under the Asura form.
El's hands kept an OK gesture while using clairvoyance to lock on Vander Decken IX's position.
Soon their figure flew out of the sunlight tree area of influence at a very fast speed and directly plunge into the dark sea where you can't even see your fingers right in front of you.
It only takes a half-hour or so, for El to reach Vander Decken IX's position, looking at the view below him, there is a ghost ship that is close to impossible to spot without night vision, and in a certain room in the ship cabin, at this time, there is a lamp that shines faintly under the protection of the Bubbly Coral and not far from it, there is a bullhead shark Fishman sitting with most of his body hidden in the dark.
Seeing this, El stretch out his palm outside the Bubbly Coral, and a small amount of their stamina was lost and converted into Float-Float Fruit ability that seized control of the surrounding seawater, then he withdrew his outstretched palm that was exposed to seawater back inside to the Bubbly Coral and then he slowly raises his hand and clenched hard.
In instant, the seawater near the ghost ship below, as if being endowed with spirituality, it automatically rotated and soon formed an incomparably huge water vortex that mercilessly crashed into the tattered ghost ship.
The underwater pressure in the deep-sea area is strong, so the water vortex that appears in the deep sea is even more terrifying than the tsunami.
So the ghost ship with an unknown history that encounter the water vortex instantly resembles a glass that turns into countless fragments after falling, among those fragment was Vander Decken IX who was revolving around the water vortex without any resistance while being punctured by several sharp planks of wood.
After seeing him lose consciousness, El waves his hand again and consumes some stamina to restore the violent water vortex back to its original appearance, then under Violet's shocked gaze, El flew over and grabs Vander Decken IX who was unconscious, and flew back towards the Fishman Island.
After another half an hour or so, El passed through the protective film again and landed on Pegasus deck, then he burst the bubble wrapping his body and let Carina release the Asura form, while the hand holding Vander Decken IX's neck tightened that ended his life.
Then while in front of Violet, Carina put Vander Decken IX' body into the big box that they prepared a long time ago and eat it, in less than a minute, Carina spits out the big box again and open it to take out the devil Fruit, while Violet who was watching this instantly turned pale.
El looks at Violet who was completely shocked while carrying Vander Decken IX's body then he turns his gaze to Carina.
"I'll leave first to recruit our new companions, Carina, you put the devil fruit in the storage first and then follow me with Violet."
"No problem." Carina also looked at Violet who was frightened with a playful smile before making an ok gesture to El.
After successfully capturing the fourth rule type devil fruit, El did not return to Ryugu Palace with Vander Decken IX's body or find Nami and other girls, instead, he flew straight to the Hard-Shell Tower direction.
It's where Shirahoshi has been locked up and raised inside for most of her life thanks to the constant threat of Vander Decken IX and if he doesn't exist then according to the plot, she will stay here for a few more years, and wait until Luffy arrival before being able to come out, but with his existence, countless people destiny has been changed and Shirahoshi is one of them.
Stopping in front of the Hard-Shell Tower that looked like a prison, El threw Vander Decken IX's body on the ground and then he reached out and touched the heavy gate.
The next second, the door with many weapons inserted into it instantly liquefied and create a huge hole, then his figure passed through the hole and he sneak into Shirahoshi's room.
In the manga, she has not left her room for more than ten years but her beauty has spread to the land and she was recognized by countless people in the world as the most beautiful mermaid.