So at first I was thinking "Why doesn't Kuroko just teleport to the other side of the door to get to Mikoto?". Then I realized this was original artwork... and that "Mikoto" was a trap... oops.

Pixiv title:

開けてよ、おにぃちゃん。……。開けろっつってンだろッ！ごるァ!！

Commentary:

ごめん、助けてあげらんないや (-_-)/

Pixiv title:

Hey, open the door Onii-chan. ...Open this door! HEY!!

Commentary:

Sorry, you won't get any help from me. (-_-)/