NatsuRin

 is the slash ship between Natsuya Kirishima and Rin Matsuoka from the Free! fandom.

Dive to the Future
FIRST SWIM IN ANOTHER COUNTRY!

Rin is talking to his teammate David, when his other teammate Chris runs by. He tells the two about Natsuya challenging everyone till Mikhail agrees to be his coach. The three run down to the pool and see Natsuya. Natsuya steps out of the pool, calling all the people he just beat slow. He turns around and sees that Rin has just walked in. He asks who he is and if he’s racing next. Rin stares at him slightly annoyed, but agrees. Natsuya is surprised to find that he’s japanese, but then Mikhail stops Rin before he can go through with the race. Mikhail says that no matter how many guys Natsuya beats, he’s not going to be his coach. Later, Rin takes a break during practice and sees Natsuya in the stands, not looking very happy.

Rin walks out of practice and stops, Natsuya is there waiting for him. The officially introduce themselves to one another, and Natsuya asks him to go have dinner. At dinner Natsuya drinks and Rin asks if he’s drinking too much, since he’s a competitive swimmer, but Natsuya says that he isn’t one. He travels around and only does competitions that have prize money. Rin thinks that’s too bad since he’s such a good swimmer. Natsuya asks about Rin going to Sano, since he went to Iwatobi. Rin asks if he knew Haru, and Natsuya confirms that he did. He asks if he went Sano in middle school, but Rin didn’t. He was already in Australia training for swimming. This impresses Natsuya given his young age. He asks about Haru and Rin confirms that Haru is still swimming and aiming for the global stage like him. Natsuya says that he’ll probably end up being his little brother’s rival. Rin asks about his brother, but Natsuya seems to have passed out. Rin then helps him back to his hotel.

After another practice Natsuya and Rin walk out to have dinner again, when Natsuya gets a text from Hiyori telling him about Ikuya. Rin asks if the text if from his brother, but Natsuya says it’s his friend who he met when studying abroad. Rin asks if his brother went abroud to train for swimming. Natsuya pauses but doesn’t answer his question, instead asking if he and Haru are friends, and tells him about the relay that Haru and Ikuya did together, and how alone Ikuya felt after everyone on the team quit, so he went to America with Natsuya. Despite how good Ikuya is at swimming, Natsuya worries that he’s going to hit a wall. He wants his brother to reach the global stage, and Rin asks if Natsuya also wants to. Natsuya says that he swims whenever he wants and doesn’t need to. Rin asks why he wants Mikhail to coach him then. Natsuya says it’s to get better, but Rin see’s some of himself in Natsuya. He’s about to ask what his dream his when Natsuya interrupts him and asks if he wants to race. Rin says that there wouldn’t be a prize, but Natsuya just says that they’ll bet something. Natsuya eventually come up with him staying at Rin’s as his prize and Rin agrees to race. They go to the pool and begin to race, when it starts to rain. When they get out, Natsuya says that they’ll save their race for later. Rin asks if he has a place to stay, but Natsuya is going back to Japan, tells Rin that it's been fun and leaves.

Moments
First Swim in a New Country!
 * Rin and Natsuya both confirm that Mihail is using outdated slang
 * Natsuya comments on Rin’s name sounding like a girls
 * Natsuya rests his arm on Rin’s shoulder startling him
 * When the other members of the team notice how often Natsuya waits at practice, they tell Rin to stop having dinner with him. Rin says that it’s okay. Natsuya’s not so bad.
 * Natsuya call Rin Adulturous, given the amount of guys he wants to swim with

Fanon
The two interacting was very unexpected for the show, given how different their places in the story were. Rin being introduced in the first episode of Iwatobi Swim Club, and Natsuya not being introduced till the prequel film High Speed. Despite this many enjoyed their interactions.

Fans took note of how when the two were first introduced to each other, how quick Natsuya was too challenge Rin, as well as how quickly Natsuya stuck out to Rin. Shippers also interpreted some of Natsuya's comments to Rin as flirting. He's also constantly smiling and winking at him, which also add fuel for shippers.

Fandom
AO3