He falls in love with her very early in the story and often flirts with her and teases her. At the start of Manga/Anime Misaki disliked all men, but that didn't stop her from letting Usui into her heart. They are currently engaged, although their relationship is still somewhat the same. She still refers to him as "her stalker" or "Perverted Alien"
Usui is only open about himself to Misaki and loves her immensely. He always saves her from trouble and gets very frustrated when she puts herself in danger. Most recently in chapter 81, as it turns 12 o'clock midnight on Misaki's birthday, Usui proposes to her and gives her an engagement ring for her birthday present.
Shintani is Usui's main rival and the only one he takes seriously, and they are usually represented as two dogs growling at each other whenever they are battling for Misaki. Usui often gets jealous of Shintani when Misaki is with him or Misaki is paying more attention to Shintani than to him. When these situations happen, Usui sometimes pulls Shintani away from Misaki, and when Shintani gets too close he often likes to remind him that Misaki is his.
Yukimura is the vice president of the student council at Seika. Misaki describes Yukimura's relationship with Usui as being "more like a pet". Usui frequently sexually harrasses Yukimura for fun and to get attention from Misaki, although the first time he did this was to convince Misaki that he was not serious about her so that she would not feel embarrassed around him.
Gerard is Usui's older English half-brother (they share the same mother), who first makes his appearance at the end of chapter 50. He and Usui look almost identical, except that Gerard's hair is straight and black. When he wore a blond wig, most people around him thought that he was Usui, although Misaki was not fooled. Gerard is an active part of the Walker family's plan to control Usui, and helps in the tracking of Usui and the plan for his transfer to Miyabigaoka. His Japanese is fluent, although he and Usui usually converse in English. Usui and Gerard's relationship does not seem to be very good, which might possibly be because of Gerard's interference with Usui's life and relationship with Misaki.