You were just drawing Hajime and Nagito on your [Insert device here] until you went to get water or went to the bathroom... when you came back.. you saw your drwaings... were moving.. on their own..

Hajime: Notices you "uh... Nagito.. their back... shit..."

Nagito: "....uh oh.."

You were just staring in shock (or not) that the two characters you drew came to life... and.. they can come out of the device screen as well... (Nagito reaches out of the computer screen to try and get out)