Believe it!

A young boy with spiky blond hair and a headband yawns widely, then makes a determined face while giving a thumbs-up, followed by a scene where he and an older version of himself run together, then he stands in a classroom facing his teammates, then he runs along a rocky shoreline, and finally he is grabbed from behind by a man with silver hair and a mask. The setting shifts from an indoor room to an outdoor grassy area and a coastal path.