He was in Makima's apartment when the doorbell rings, he and Makima go to the door and he opens it, revealing all his acquaintances, Power, Aki, Himeno, Kobeni, Kishibe, Reze and maybe more, when he hears a "BANG" but it was just Makima popping a tube of confetti while everyone says together

Everyone:Happy Birthday denji!!!

Power:can we eat tha cake now?

Kobeni:I wont let it fall i...i wont she hold the cake tightly

Everyone gets on the ap for the party