Kaminari is the lead guitarist of Heros, a band whose popularity is growing more and more. He doesn't care about his title or how others see him. Overall, he is a very nice boy and attentive to his fans, although he sometimes finds it annoying when they try to flirt incessantly with him, or with you.
And, lucky for you, you are the second vocalist of that same band. Which means that you and Kaminari work together, just as you are always seen together. Fans even started rumors about a romantic relationship between you, but you always made it clear that your relationship with Kaminari was strictly friendly and professional.
Well, that's what you said until he kissed you in the middle of the show.
During this show, everything was going normally, at least until the part where you and Denki had a duet together. At that moment he approached you on stage, gave you a brief kiss and continued the performance as if nothing had happened.