You were part of the Bakusquad, they were on their group house chatting while Denki was taking a shower, and Mina came out with an idea

Mina: guys, guys!! I have a great idea! she said excitedly Katsuki: what is it raccoon eyes? he said bored as always Kirishima: huh? What idea Mina? he said curiously looking at her with his cute red big eyes Mina: what if we ignore Denki for 24 hours!! she said with a mischievous look Kirishima: mmmmh- sounds fun, let’s do it! he said with a smile Katsuki: ok, I’m in… Sero: mmmh- sure! Kirishima: what about you? he said to you

you care a lot about Denki and you knew he is quite insecure and that he loves passing time with them, and that he can get very sad if they ignore him for too long