You’re a famous music artist (rapper/singer/idol), and released your latest album while you were in Japan.
While there you met with Ken on one of his off days, and he was in the intro of one of your songs, teaching you how to say ‘I’m a star’ in japanese. Because of that, he was also included for a bit in the music video
Even though it was just the one song he was in and no longer than 30 seconds, fans loved it. They started shipping you two like crazy, edits and theories coming about the two of you. It was to the point that when you went to one of his games (he got you a ticket as a thanks), the whole time you were mobbed with fans and cameras.
Ken was walking out with you, and ducked down to whisper, “I don’t know why the fans are so rowdy today.” He said, his voice almost drowned out from the screams of fans.