The story of One Piece is a sprawling saga of adventures on the high seas, the power of friendship and trust, and a whole lot more. All of these themes and more are embodied in the hero, Monkey D. Luffy, a boy of endless optimism and courage. He loves the open sea and the adventure it brings, and he loves his Straw Hat crew, too.
But is there anyone near and dear to his heart outside his crew and family? Not especially. It's Sanji Vinsmoke who's head over heels for Nami, and Luffy is hardly even aware of Boa Hancock's fierce passion for him. But in theory, if Luffy met potential lovers from other anime series, who would win his heart, and how? Ideally, Luffy will meet someone who has a similar personality and worldview, someone he can share his quest and his heart with.
10 Yoruichi Shihoin, The Fun-Loving Assassin (Bleach)
At first, the assassin Soul Reaper Yoruichi Shihoin seems totally different than Luffy, given her occupation and her lack of experience on ships and the open sea. But on second glance, it's clear that this elite Soul Reaper actually has a lot in common with that rubbery pirate captain.
Like Luffy, Yoruichi is a whimsical, fun-loving free spirit who can eat an astonishing array of food to fuel up before or after a fight. Yoruichi is an independent-minded person who values loyalty and friendship over the law, and Luffy can appreciate that. He's never met a potential date like this before.
9 Nobara Kugisaki, The Hard-Hitting Sorcerer (Jujutsu Kaisen)
At first, Nobara Kugisaki might get an iffy impression of Luffy if they ever met, since Nobara is a no-nonsense sorcerer who puts the mission first. But if Nobara got to know Luffy better, she would recognize him as a kindred spirit, someone who will fight to the death to defend the people dear to him. His courage would appeal to her, too.
Nobara would warm up to Luffy before long, and Luffy, in turn, would be wowed by Nobara's stylish sorcery and her tough but fair attitude. Nobara does have her warm and gentle side, and she and Luffy could have all kinds of adventures together.
8 Shion, The Gung-Ho Ogre (That Time I Got Reincarnated As A Slime)
In the original anime, the ogre Shion has eyes only for Rimuru Tempest, since that isekai hero helped give the ogres a new purpose and a new home. Shion would easily get along with other shonen heroes too, especially those who share her fun-loving and carefree personality.
Shion, like Luffy, always listens to her heart and knows exactly what she wants. She would be enamored by Luffy's intense loyalty and love of his crew, and if he and Shion ever fought together or had an adventure together, they just might take their friendship to the next level.
7 Sasha Braus, Who Lived Free (Attack On Titan)
As a whole, it is likely that Luffy will prefer girls who are goofy and carefree like him, but also loyal and honest to themselves and others. Sasha Braus, a scout, also fits the bill. She even sailed on the sea once, traveling to the distant Marley Empire with her friends to scout the place undercover.
Sasha is a tough and kind country girl at heart, and she will always stand up against evil and do the right thing, even at great personal risk. Luffy is always on the lookout for people like that, and Sasha's warm personality would definitely inspire him.
6 Avatar Korra, The Headstrong Waterbender (The Legend Of Korra)
Ultimately, Avatar Korra realized that her heart belonged to her dear friend and teammate Asami Sato, but before the, she was open to dating the brothers Mako and Bolin. Given her personality and worldview, Korra would have been open to dating Luffy as well during that time.
Korra and Luffy are both classic shonen heroes, being stubborn and independent but also loyal to their friends and always seeking hard-won justice. Korra and Luffy would get along great and have all kinds of fun date nights in Republic City's night scene.
5 Nejire Hado, The Shockwave Hero (My Hero Academia)
Nejire Hado is one of U.A.'s "big three" students, and for good reason. This third-year has a powerful Shockwave Quirk that can convert her life force into powerful, spiral-shaped blasts of energy, and she can even use it to fly around. Luffy would mistake this power for a devil fruit at first, and no one could blame him.
On a personal level, Nejire is a lot like Luffy, being whimsical, carefree, and fiercely dedicated to protecting the innocent and upholding justice at all costs. She and Luffy would get along famously, and Luffy would soon realize that Nejire is someone very special to him.
4 Lucy Heartfilia, The Celestial Summoner (Fairy Tail)
In the original show, Lucy Heartfilia is the sweetheart of Natsu Dragneel, whose fiery temper and personality are remarkably similar to Luffy's (aside from the literal fire). Clearly, Lucy has a thing for gung-ho boys who are true to themselves, and Luffy would find more than a few things to like about Lucy, too.
Lucy was born into old money, but she longed for adventure and wanted to prove herself on her own merits. Luffy would definitely admire that, and he'd also approve of Lucy's emphasis on friendship and loyalty to a guild or crew. All that, combined with Lucy's sharp wits and flexible combat style, would make Luffy fall for her before long.
3 Tomoko Higashikata, A Fierce Joestar Mother (JoJo's Bizarre Adventure)
Tomoko Higashikata is a neat fit for Luffy, mostly because of her outstanding personality and her bravery. Tomoko does not have a Stand of her own, but she is tough and takes no nonsense from anyone. She is also a loving mother and a fierce fighter against home intruders (even if they have a Stand).
Luffy would definitely give Tomoko a second glance, and he would love her strength of spirit and dedication to her family. She is also sweet and gentle for the most part, and Luffy would find her simply dazzling. She needs a spot on the Merry Go ASAP.
2 Diane, The Gentle Giantess (The Seven Deadly Sins)
Diane is a member of the Seven Deadly Sins team of knights, and she represents the sin of envy. Diane isn't completely green with envy, though. For the most part, she is highly supportive of her friends and is happy for them, and she has a big heart to match her titanic size.
Diane didn't have many friends growing up, and she felt excluded from the other giants of Megadozer due to her semi-pacifistic ways. Luffy, however, would accept Diane for who she is, and they would get along wonderfully as they go on adventures together and get to know each other better. There's no denying Diane's charm, as Luffy will soon find out.
1 Ms. Joke, The Laughter Hero (My Hero Academia)
Nejire isn't the only My Hero Academia hero who may capture Luffy's heart. There's also Ms. Joke, a young woman who teaches at the Ketsubutsu heroics school. True to her hero name, Ms. Joke can make people laugh with her Quirk, and she has a fun-loving personality to match.
Ms. Joke's easygoing and sparkling personality would make a big impression on Luffy, and her serious combat skills and dedication to her students would definitely endear him to her. Students are like crew, in a way, and Ms. Joke takes good care of her crew. She and Luffy could have all kinds of adventures together.