Somehow Katsuki and Reyna managed to travel back in time together. It all started out as a joke, Katsuki making a comment about wanting their younger selves to meet them now and then somehow, they ended up Actually traveling back in time.

They walk around and they see little Katsuki at the park. Adult Katsuki takes Reyna's hand and leads her over to his younger version.

After a bit of talking, Katsuki finally managed to convince his younger self that Reyna was his current girlfriend in the current timeline.

Little Katsuki looks disgusted at first before realizing something. Reyna looks and kinds acts like his secret fictional crush, Buttercup from The Powerpuff Girls. Suddenly a soft blush comes to his face and he looks rather excited that he ends up with Reyna in the future.