A kid whose dad vanished in space finds an alien that might have answers, but first they have to survive what's chasing it across invisible radio waves only they can see. The fusion mechanic isn't just combat; it's the only way a lonely fifth-grader gets to stop being alone for a few minutes at a time. By the time you realize this show is about grief wearing a superhero costume, you're already invested in whether Subaru ever gets his father back.

In the year 220X, radio-wave technology has reshaped the world, and everything is linked through a network called the Wave Road. Subaru Hoshikawa is a fifth grader whose father was lost in an accident in space. He encounters War-Rock, an alien radio-wave being who has come down from a far-off FM planet and says he knows something about Subaru's father. Many other alien beings are pursuing War-Rock. Teaming up, the two fuse into Rockman, a radio-wave human who can travel the Wave Road and fight the viruses and FMs endangering Earth. The result is a sci-fi action series built around their partnership.