"What’s The Outsiders?" by m.c.A・T is the official theme song for the Kamen Rider Outsiders miniseries, released on October 16, 2022, under the avex trax label. The track explores themes of individualism and raw power, aligning with the show's focus on anti-heroes and villains from the Kamen Rider multiverse. The "What’s The Outsiders? EP," featuring the full, short, and instrumental versions, is available on major streaming platforms and digital stores, including the Amazon Music Store .