Mt. Kamui

Mt. Kamui is the het ship between Yu Takeyama and Shinji Nishiya from the My Hero Academia fandom.

Canon
Yu and Shinji are both introduced in the first episode of the anime as Pro Heroes Mt. Lady and Kamui Woods. They both fight the villain that had appeared in the city, but Yu, who is making her debut as a hero, ends up getting all the credit for taking him down, which Shinji is not happy about. They do work together fighting villains during the U.S.J incident, and as guards during U.A.'s Sports Festival. There, Yu uses her good looks to get free food, and Shinji critiques her for having no shame. She later teases him for having a quirk similar to one of the U.A. students

Yu and Shinji take a car together to the League of Villains' hideout. Near the end of the fight, Yu is knocked unconscious, and Shinji rescues her, telling her she did a good job. They are good friends after this, and form a team with a fellow Pro Hero Edgeshot, dubbed 'The Lurkers'. During the Hero Billboard event, the whole team is present, Shinji being in the top ten, and Yu is disappointed she hasn't reached it yet. Interviewers then approach Yu about Shinji, and she says she's learned a lot from being on the same team with him. She is then asked about the rumors of them dating, but simply smiles and declines to answer.

The Lurkers eventually take on several work study students, including the U.A. girl Yu had mentioned to Shinji. During the Paranormal Liberation War, they take on Gigantomachia together. They both show immense concern for each other. Shinji yells for her when she is tossed to the ground, and Yu worries for him when he is knocked out by Midnight's quirk.

Fanon
This pairing is the most popular for both characters, due to how often they are seen together and being rumored to be together in-universe. Fans enjoy the growth of their relationship from rivals to close friends.