Kakusei

Kakusei, or Awakening in English, is a Japanese pop rock song featured in the movie Promare. The song can be found in Superfly's Ambitious album alongside "Kori Ni Tojikomete." It was also briefly in the YouTube short-film "The Ancient Beings Strike Back" uploaded to the Dr Billy YouTube Channel, as the leitmotif of Billy. It is also used as Billy within this universe's leitmotif.
https://www.youtube.com/watch?v=7u052cW1e1Y