Following the TV premiere of the summer 2026 anime The World's Strongest Rearguard in Japan, the music videos for the opening and ending theme songs were released on the artists' respective official YouTube channels. The six-member rock band from Kyoto, Redhair Rosy provides the opening theme song "license." This is their first anime tie-in song and is included in their major debut double A-side digital single, "Kakeru / license," which was released on July 3. Redhair Rosy "license" Music Video The World's Strongest Rearguard Creditless Opening Video Comment from Redhair Rosy's vocalist Ryosei: Walking through an unfamiliar city, I sometimes feel as if I am in a labyrinth. When I witness a small miracle, it can feel like magic. I wrote this song by drawing parallels between my own environment and the strength found in moving forward with friends—having someone you can trust to have your back. I hope this song, overlaid with the image of Arihito and his friends taking on a seemingly reckless battle while believing in each other, can provide even a little bit of energy or courage. Redhair Rosy artist photo Meanwhile, the two-member rock band Inner Journey performs the ending theme "Owaranai Yoru no Mamorikata" ( A Way to Guard the Endless Night ).