One Piece: I Am the Swordsman Ryuma

Ryuma transmigrates and wakes up to discover that he has become the legendary dragon-slaying samurai swordsman of ancient times. He gains a System and kills one of the Shichibukai, Gecko Moria, from the start, obtaining the S-rank Shadow-Shadow Fruit! Doflamingo: “Could that really have been the ancient Ryuma, the one who ruined my Devil Fruit sales plan?” Akainu: “That bastard is much more troublesome than I expected. He took Kaido’s position and still refuses to join an Affiliated Nation!” ... From then on, Ryuma keeps absorbing Devil Fruit abilities and learning ever more powerful combat techniques as he makes his way to the summit! Ryuma: “Anyone who dares invade Wano Country, no matter how far away, will be put to death!”