Yet again when the
decorations went up, Setsuna was caught by surprise and realized Kira's birthday must have passed, once more, without recognition. Flailing, annoyed at himself, Setsuna grabbed some ice cream, a couple of sodas and some pizza, then rushed back to the theatre, hoping he could find Kira.
He half wanted to throw Kira a surprise party like Kira had done to for him, but Setsuna didn't want to wait too long to celebrate, and didn't feel like planning since he'd already failed to keep track of time properly, even for guestimating purposes. So, instead, he decided a personal little party would feel more like old times, and therefore be more special. But one day, he promised himself, Kira was getting a huge surprise thrown at him, one way or another. Eventually.
Setsuna closed in on Kira's aura in the back and found the other male reading - not surprising - and shouted a bit, "Happy birthday!" hoping to startle Kira before he realized Setsuna was there. If not that, then at least make it clear to anyone else in the theatre it was time to go bug Kira.