"IDOLiSH 7 TRIGGER -before The Radiant Glory-" is a manga that serves as a prequel to the main "IDOLiSH 7" series, focusing on the formation and early days of the idol group TRIGGER. The story centers on the three members of TRIGGER: Ryunosuke Tsunashi, Tenn Kujo, and Gaku Yaotome, exploring their individual backgrounds, motivations, and the circumstances that led to their collaboration as a group.

Ryunosuke Tsunashi, a former child actor, struggles with the weight of his past fame and the expectations placed upon him. His decision to pursue a career as an idol stems from a desire to redefine himself and escape the shadow of his earlier success. Tenn Kujo, a prodigious and enigmatic figure, is driven by a deep-seated ambition to rise to the top of the idol industry. His cold and calculating demeanor often masks his true feelings, creating tension within the group. Gaku Yaotome, the son of a wealthy and influential family, initially views his idol career as a means to rebel against his family's expectations. However, as the story progresses, he begins to take his role more seriously, developing a genuine passion for performing.

The narrative delves into the challenges the trio faces as they navigate the competitive and often cutthroat world of idol entertainment. Their differing personalities and conflicting goals create friction, but they gradually learn to work together, forging a bond that strengthens their group dynamic. The manga also explores their interactions with key figures in the industry, including their manager, Tsumugi Takanashi, and other members of the idol community, providing insight into the broader context of their journey.

As TRIGGER begins to gain recognition, they must confront internal and external obstacles, including rivalries, personal insecurities, and the pressures of fame. The story highlights their growth as individuals and as a group, culminating in their rise to prominence as one of the leading idol units in the industry. Through its focus on character development and interpersonal relationships, "IDOLiSH 7 TRIGGER -before The Radiant Glory-" offers a compelling exploration of the struggles and triumphs of aspiring idols.