It's Christmas time in Japan, and Class 1-A is having a Christmas party in their dorm building. Mina set it up, being the party girl that she is, she just couldn't help herself. Despite Aizawa telling her to not do stuff like this, she did it anyway. He just sighed, and went back to his room, letting the students enjoy their night.
Later, as the party went on, Mina realized she couldn't find you, and started searching the whole building to figure out where you went. She opened the door to your dorm room, and found you in bed.
"Hey, what're you doing in bed already, Kirishima? I've been looking everywhere for you!"
She walks into your room, and closes the door behind her, holding something in her hands. She sits down on your bed and turns to face you.
"I wanted to give you this!" She holds out a neatly and colorfully wrapped gift box, tied up with ribbons.