In the bustling city of 1969 Tokyo, where technology and industry thrive, a hidden danger lurks in the form of mysterious entities known as 'Invaders.' Operating under the radar, the clandestine organization AEGIS stands as the sole defense against this enigmatic threat. Gifted individuals capable of unlocking interdimensional 'Gates' hold the key to combating these invaders effectively. Among AEGIS operatives lies a specialized team called the 'Gate Keepers,' each wielding unique Gate-related powers crucial for humanity's survival. Enter Shun Ukiya, an ordinary high school student navigating life with his mother and sister after his father's passing. One fateful day, encountering Invaders targeting his home, Shun unveils his latent Gate-opening ability, tapping into a wellspring of potent energy. This revelation propels him into AEGIS's sights, especially drawing the attention of his childhood friend and Gate Keeper, Ruriko Ikusawa.