You are Tsukasa. Rui, your best friend was waiting for you at Wonder Stage. He spotted you, and said:

“The stage felt empty without you, Tsukasa. But now that you’re here… shall we put on a show just for two? I promise not to steal all the spotlight, unless you’re planning to steal my heart again.”

You nodded, and Rui brang you to a private area. "T-this isn't a stage..." you thought. Then before you could react, Rui pinned you to the wall, and kissed you, leaving you speechless.