Warning: Contains spoilers for One Piece chapter #1046
Pirates and ninjas do not have much in common, usually, but in the world of One Piece, one heroic shinobi just saved every major character in the series, using a technique straight out of Naruto.
The island of Wano is the setting of One Piece's current (and longest) arc. It is strongly inspired by feudal Japan, with a ruling class of samurai who serve under a shogun, the usurper Kurozumi Orochi. In such a setting, ninjas could not be missing, and Luffy and his crew met one as early as chapter #817, long before they even reached Wano. Raizo of the Mist is a ninja and a retainer of the Kozuki clan, one of the Nine Red Scabbards that served the legendary samurai Kozuki Oden 20 years before the current events in the series. Together with three of his fellow Red Scabbards and with Oden's son, Momonosuke, Raizo was sent 20 years in the future by the powers of Toki, Oden's wife, to protect her son and prepare the rebellion against Orochi.
Raizo got separated from his companions after leaving Wano to find allies. He was able to reach Zou, the land of the Mink tribe, longtime allies of the Kozuki, and that's where Luffy and the other Straw Hats met him. The always-enthusiast pirates asked Raizo to demonstrate his ninjutsu techniques, which he reluctantly did. All of his techniques seem inspired by Naruto's jutsu, including the shadow clone jutsu and summoning jutsu. In fact, it appears that Raizo is an homage to depictions of ninjas in various media, including Naruto, and that would make perfect sense considering that the artists behind these two best-selling manga, Masashi Kishimoto and Eiichiro Oda, are actually good friends, and Naruto even paid homage to One Piece in its last panel. Coincidentally, both the Japanese and English voice actors for Raizo in the anime also voiced Naruto characters.
In chapter #1046 of One Piece (titled Raizo of the Mist), the battle between the Ninja-Pirate-Mink-Samurai alliance and the forces of Kaido was about to reach an unexpected conclusion. With the flames created by Kanjuro's dying technique spreading through all of Onigashima Castle, everyone involved in the battle was about to burn alive or suffocate. Even Luffy and Kaido, fighting for supremacy on the roof, acknowledged the danger, but that's when Raizo stepped in. Raizo ate the Maki Maki no Mi, a Paramecia type Devil Fruit that allows him to create and manipulate scrolls, which he can use to seal and store objects inside and later release them. When on Zou, he used his power to store an impressive amount of ocean water and released it inside Onigashima Castle. Thanks to Jinbe's ability to manipulate water, that massive current spread throughout the halls and corridors, saving everyone from a gruesome death.
Many ninjas in Naruto use scrolls to summon objects with a technique called fūinjutsu, most notably Tenten, a kunoichi and member of Team Guy. Raizo's epic intervention, however, has an even greater significance. Twenty years ago, he was unable to save his master Oden and watched helplessly as Kaido set the Kozuki castle ablaze. Raizo swore that he would never be as helpless again, and he just stayed true to his promise, saving all of his allies, including every member of the Straw Hat crew. It was a beautiful moment that showed how much Oda cares about even his secondary characters, and a further homage to Naruto, one of the few mangas in history that can get close to One Piece in terms of success and popularity.