Deku, Bakugo, and Todoroki participate in internship under the No.1 hero, Endeavor's agency. One of their tasks these days is to find a villain (“Smiley”) who draws doodles in the city. However, since the urgency is so low, they let other pro-heroes solve this case. One day, Smiley draws a doodle on Endeavor’s house! Being furious, Endeavor himself and the 1-A trio go out to get the villain. However, Smiley’s quirk turns out to be something ridiculous but powerful... It is to make anyone who looks into his eyes laugh hysterically! Can the team capture the villain and stop laughing!?