"Mjolnir: A powerful enchanted hammer so heavy that no one could lift it. There are only 3 known Mjolnir in Asgard. Roronoa Zoro managed to lift all 3 of them, 2 of them with hands and 1 with his teeth. The badass achievement of lifting all 3 Mjolnir has earned him the title of Thor, the one who mastered the art of San-Thor-Ryu."
The art depicted Zoro holding a hammer in his teeth was not only effective, but the "San-Thor-Ryu" pun has fans in tears. There is a fan debate whether or not Zoro would be worthy in the Marvel Universe, but the fantasy of it is just too much fun to poke holes in overall.
Fans have run with the crossover and lovingly crafted puns of their own, dubbing the mash-up as "Roronoa Thoro" and have even gone as far as wondering whether or not "Thoro" would be stronger than Luffy. But fans have quickly pointed out that even with three thunder hammers, "Thoro" would not be able to harm Luffy since Luffy's rubber body would negate all of the lightning powers much like in his battle with Enel.
This isn't the only anime and Disney crossover either. Kohei Horikoshi of My Hero Academia recently designed a poster celebrating the release of Star Wars: The Last Jedi and Japanese voice of Thor in Thor: Ragnarok is provided by Kenta Miyake, the voice of All Might.
Eiichiro Oda's One Piece first began serialization in Shueisha's Weekly Shonen Jump in 1997. It has been collected into 87 volumes, with a few chapters yet to be included. It has been a critical and commercial success worldwide with many of the volumes breaking printing records in Japan. The manga has even set a Guinness World Record for the most copies published for the same comic book by a single author, and is the best selling manga series worldwide with 430 million copies sold worldwide.
One Piece is currently in the middle of the "Whole Cake Island" arc and is now streaming on Crunchyroll and FunimationNOW.