The three were sitting in the room in silence. Before they heard a large explosion outside. "Hey! He's back!" Kai said as he looked out the window and saw Wapol trying to break into the castle. Luffy ran by the room at this time and looked out the window. "He survived! I get to fight him this time, right Mask guy?" Kai just laughed and nodded and Luffy jumped out the window. "Shishishi! Come here, mouth guy! Let's fight!"
Before he could fall Chopper turned to his human form and caught him. "You can't fight him! He's really strong and you're injured!" Luffy just looked at him weird. "But I'm bored! I wanna fight someone!" Chopper face planted as he heard this, accidentally dropping Luffy in the process.
"Shishishi! Thanks, fluffy guy!" Luffy said as he ran towards where Wapol just was. Only to find him missing. Sanji and Kai hopped out the window as well and they ran into Kuromarimo. One of Wapol's subordinates. He started throwing black balls at them that got stuck to Sanji. Kai just flipped back and dodged all of them and decided to geppo up to the roof to watch the fight.
Chopper saw this and asked Nami. "What is wrong with that guy? Did he just run on air?" Nami sighed. "You get used to it." She gasped and grabbed her own mouth. "What did I just say? What's wrong with me? I must still be sick." Chopper checked her temperature. "No. You're completely fine now." Nami turned pale. "What's happening to me? Did I really just accept the fact that people can walk on air?" She got up and left the room. "I need to find some money." She said as she left. On her way to look for a treasury she passed Wapol and stole an important looking key from him.
Luffy was running through the castle looking for Wapol. When Luffy finally found him and he was standing in front of a door looking at his waist and emptying his pockets. "It was right here! I had it a minute ago!" Wapol was standing in front of the treasury looking for his key, which Nami stole.
"There you are!" Luffy yelled as he punched Wapol in the face, sending him through the wall out of the castle. Wapol landed outside and Luffy chased him out as he jumped throught the hole in the wall. Luffy landed next to Chopper.
Wapol got up and turned into a cannon. "Why is that goddamn dead man's pirate flag on MY castle?" He aimed up at the flag that was flying on top of the castle and as he was about to fire Chopper yelled. "No! Stop! That's the last thing I have from Dr. Hiriluk! Please don't!"
Wapol just laughed at Chopper's misfortune. "Maaaahahaha! This is what he deserves for defying me!" He shot multiple cannonballs at the flag. Luffy stretched his arm out and flew towards the flag and Kai stood up and jumped towards it as well. Luffy landed next to the flag and held it in one hand as Kai landed in front of him and slashed threw all of the cannonballs making them all miss the flag. He sheathed his sword as he stood next to Luffy.
"This is Chopper's last memory of someone important. I won't let you destroy it!" Luffy yelled as he handed the flag to Kai. Kai grabbed it from him and planted it in the roof behind him. Sitting in front of it to protect it. "I'm gonna kick your ass Wapol!" Luffy yelled and jumped off the roof landing in his signature position with a fist on the ground and his legs spread out.
Chopper started crying tears of joy. "But I'm just a monster!" Luffy looked at him and laughed. "Shishishi! Then you can be our monster!" Chopper was surprised by this and kept crying. "Hey Luffy! He isn't a monster! He's a dog!" Kai yelled from the roof.
"I'm not a dog! I'm a reindeer!" Chopper yelled at him but it didn't have any hatred in it, only appreciation. Kai laughed. "Wahahaha! The crew really needs a doctor! You should come with us! They need you!" Chopper turned shy. "It's not like I'm happy you need me or anything!"
"Shishishi! Join us Chopper! You woul-" Luffy said before he was cut off by a house hitting him. It was Wapol in his Chessmarimo form. Luffy got up and sent a gomu-gomu no gatling gun at Wapol who was much stronger now and stood his ground. Sanji went to join the fight but Kureha chopped him in the neck, knocking him out. "You haven't recovered yet."
Eventually Luffy got knocked down and Chopper stepped up to fight Wapol. He showcased his rumble balls and started dealing damage to Wapol, but just as it seemed like he was about to land a finishing blow in horn point he reverted back to normal and dropped to the ground.
Luffy caught him before he hit the ground. "Shishishi! You're pretty strong too! You need to join my crew!" He set Chopper down and said. "After I'm done with this guy, let's sail around the world together! I'll show you way more weird and cool things and prove you're not a monster!"
Kai heard this and flashed to the ground. He whispered to Kureha. "Do you know about Zou and the minks?"
"No."
"Ah I see, makes sense." He flashed back to his seat in front of the flag and continued to guard it.
Luffy started fighting Wapol again and was beating him really badly. Eventually his Chessmarimo form fell apart and he fell to the ground alongside his two retainers. Luffy saw this and winded up his arm really far back. He finally released his arm and hit Wapol in the face. Wapol flew off and became a star in the sky again. As he was flying away Kai heard him say. "We're blasting off againnnn!" Kai facepalmed. He heard him right the first time! He wanted to yell at Wapol that this is the wrong franchise but he just left it alone.
He grabbed the flag and jumped down from the roof. He landed in Luffy's pose and looked at everyone. They all held up signs with numbers on them. Sanji gave him an 8, Nami gave him a 3, Chopper gave a 7, Kureha gave a 2, and Luffy gave a 10. Kai sighed vowing to do better next time in his heart.
The crew went back into the castle and talked to Kureha and Chopper about everything that had happened and what they were going to do in the future. Chopper officially decided to join the crew, causing everyone to cheer for him. Chopper called them bastards while blushing and everyone laughed.
…
An hour later
The crew and Chopper were all ready to leave. They went to go say goodbye to Kureha. She chased them out yelling. "You bastards! You stole my assistant!" As she started throwing random things at them. First she threw a shoe, then a belt, then a book, then she threw a hat, then she threw a- holy shit is that a cabinet? She threw a full sized 10 foot cabinet that just appeared in her hand as she must have grabbed it out of space-time.
She kept chasing them all the way down the mountain until they got to the dock. She shook her fist at them as they started sailing away. Then she returned to the castle to find Dalton there waiting for her. She asked him for some help and he agreed.
…
10 minutes later. On the ship.
The crew was sailing away and having a party for Nami's health and the new crew member! It was dark out and everyone was singing and cheering. All of a sudden they heard a loud boom from behind them and they all turned around. A massive pink explosion lit up the skies and an uncountable number of sakura petals started falling down slowly. Painting a truly beautiful scene.
Suddenly a massive wing blew in and blew all the sakura petals into the shape of a beautiful tree in the sky making it seem like a real tree losing its leaves rather than just a massive ball in the sky. Kai smiled at his handiwork as he looked over at Chopper who was right beside him. He patted Chopper on his shoulder and said. "Look Chopper. That old quack really did it." Chopper was balling as he nodded. "He did it!"
The rest of the crew had warm smiles on their faces and watery eyes at this scene and they all had another round of drinks. No one would ever forget the night Chopper joined the Straw Hats!