A prologue webcomic to the Angelique Retour game, Angelique Retour Secret Side delves into the pasts of the Sacred Guardians of the Sacred Bird Cosmos, revealing the key events and relationships that shaped them before their service in the Holy Land. The narrative unfolds as a series of origin stories.

The first story examines the passionate youth of Oscar, the Guardian of Fire. As a seventeen-year-old student at the Imperial Military School, Oscar lives a life of ease until he meets Anastasia, a severe and dedicated knight serving as a new instructor. Fascinated by her strength and beauty, he attempts to woo her, but she dismisses him as a superficial boy. Challenged for the first time, Oscar abandons his playboy ways and commits to rigorous training, eventually earning her respect. He falls deeply in love with her, but his hopes for a future together are shattered when Anastasia dies in an accident just as he achieves knighthood. He awakens from this memory in the present, still carrying the earring she left with him, and reaffirms his duty to the Queen, hoping one day to find such love again.

Another arc focuses on the childhood of Julious, the Guardian of Light. From the age of five, Julious is a prodigy, groomed for his role as a Sacred Guardian. However, his perfectionism masks a deep loneliness, as his parents are distant and he has no friends. He finds a mentor in the previous Guardian of Darkness, who encourages him to be more childlike. Julious is devastated when this guardian suddenly departs, replaced by the silent and mournful Clavis. Resentful at first, Julious eventually finds Clavis in a forest, homesick and clutching a rabbit for warmth. Realizing his own loneliness for the first time, Julious vows that together, he and Clavis will become the perfect guardians, a promise he continues to uphold in the present.

The story of Olivie, the Guardian of Dreams, explores his life before the Holy Land. A sixteen-year-old with a passion for fashion design, he leaves his rural home for the capital against his father's wishes. While working as a model, he befriends Irene, a fiery rival who shares his dream of success. Their friendship strengthens him, and he decides to pursue design in earnest. Just as his career begins to flourish, he is chosen as a Sacred Guardian. He refuses, unwilling to sacrifice his dream, but a visitation from his dying predecessor convinces him that dreams bring hope to the cosmos. Before departing, he meets with Irene, who, accepting her own failed career, announces her engagement. Her happiness gives him the courage to embrace his new duty, vowing to never forget the joy of dreaming.