Cobra Kai should bring back Daniel LaRusso's forgotten girlfriend, Kumiko. Portrayed by Tamlyn Tomita, the Japanese character plays a prominent role in The Karate Kid Part II, but hasn't been part of the continued storyline through the movie franchise and Netflix continuation. Given that Cobra Kai season 3 will include an Okinawa subplot, it's the ideal time for Kumiko's return.
In The Karate Kid Part II, Daniel travels to Okinawa and learns about the family history of his mentor, Mr. Miyagi (Pat Morita). The characters bond while speaking about the deaths of their fathers, and also while discussing the martial arts traditions of Miyagi-Do. In a clever narrative twist, Daniel falls in love with Kumiko, who just so happens to be the niece of Mr. Miyagi's lost-love, Yukie (Nobu McCarthy). The film's primary conflict involves a psychological battle between Mr. Miyagi and his former best friend Sato (who was supposed to marry Yukie), along with a physical battle between Daniel and Sato's arrogant nephew Chozen Toguchi (Yuji Okumoto), who adores Kumiko but ultimately threatens to kill her. The Karate Kid Part II ends with Daniel saving the life of his Japanese girlfriend and honoring the legacy of Miyagi-Do.
The Karate Kid Part III reveals that Kumiko decided to pursue a dance career in Japan, which makes her Daniel's archetypal "lost love." In Cobra Kai season 3, she could potentially return because of her familial connection to Mr. Miyagi, and also because of Daniel's marital conflict with wife Amanda (Courtney Henggeler), who demands that Miyagi-Do be shut down at the end of Cobra Kai season 2. The specifics of Daniel's trip to Okinawa remain unclear, though it's been revealed that he will indeed re-connect with his Miyagi-Do past in Japan. So, because Cobra Kai fans are so invested in nostalgic call-backs to the movie franchise, it makes sense for Kumiko to at least return for a cameo in the Netflix series. In theory, her reappearance will benefit the storyline in two significant ways. First of all, she'll remind Daniel about Miyagi-Do traditions and inspire him to re-open his American dojo. Secondly, Kumiko may indeed still have feelings for Daniel, and vice versa, which would naturally force the characters to make some difficult decisions — good drama!
Cobra Kai season 3 should also bring back Kumiko because Tomita is still a working actress. In fact, she's assembled an impressive industry resume since making her movie debut in The Karate Kid Part II. Within the past five years alone, Tomita has portrayed Noshiko Yukimura on Teen Wolf and Allegra Aoki on The Good Doctor. She also appeared as Tamiko Watanabe in The Man in the High Castle and Commodore Oh in Star Trek: Piccard. For Cobra Kai, Netflix and Tomita may strike a deal for a cameo role, but there's a strong possibility that she could sign on for a recurring role.
Given that Cobra Kai doesn't shy away from dark storylines, it's certainly possible that Netflix may shuffle up the character dynamics moving forward. As of now, it seems that Daniel will reconnect with his Miyagi-Do past and most likely train a new student, Johnny Lawrence (William Zabka). In that case, Cobra Kai season 3 would conceptually pay homage to The Karate Kid Part II, all the while resolving the life-long conflict between the two main characters. It's also worth noting that Daniel seemingly references Kumiko in Cobra Kai season 2 while discussing his past relationships with Samantha: "That's a story for another time," he says while referring to Ali, "and there's a story after that one."