"IDOLiSH7 Third Beat!" continues the journey of the idol group IDOLiSH7 as they navigate the complexities of the entertainment industry, personal growth, and interpersonal relationships. The series delves deeper into the challenges faced by the members—Riku, Tenn, Iori, Yamato, Mitsuki, Tamaki, Nagi, and Sougo—as they strive to balance their careers with their personal lives. The narrative explores themes of ambition, rivalry, and the pressures of fame, while also highlighting the bonds that unite the group.

The story picks up with IDOLiSH7 preparing for a major performance at the Tokyo Dome, a milestone that signifies their rise in the industry. However, their path is fraught with obstacles, including intense competition from rival groups like TRIGGER and Re:vale, as well as internal struggles. Riku, the group's lead vocalist, grapples with his health issues, which threaten to derail his career and the group's momentum. His twin brother, Tenn, a member of TRIGGER, faces his own dilemmas as he tries to reconcile his loyalty to his group with his concern for Riku.

Meanwhile, Iori, the group's strategist, takes on a more prominent role in managing the group's direction, often clashing with Yamato, the leader, over their differing visions for IDOLiSH7's future. Mitsuki, the group's energetic dancer, struggles with feelings of inadequacy, while Tamaki, the youngest member, continues to mature and find his place within the group. Nagi, the group's foreign member, deals with cultural adjustments and the weight of his family's expectations, and Sougo, the group's keyboardist, faces challenges in balancing his musical aspirations with his responsibilities to the group.

The series also introduces new characters and expands on the backstories of existing ones, providing a richer understanding of their motivations and struggles. The interactions between IDOLiSH7 and other groups, such as TRIGGER and Re:vale, add layers of complexity to the narrative, as alliances are tested and rivalries intensify. The competitive nature of the idol industry is portrayed with a mix of realism and drama, highlighting the sacrifices and dedication required to succeed.

As the story progresses, IDOLiSH7 must confront not only external challenges but also internal conflicts that threaten to fracture the group. The series emphasizes the importance of communication, trust, and perseverance, as the members work together to overcome their individual and collective struggles. The narrative builds towards a climactic performance at the Tokyo Dome, where the group's unity and determination are put to the ultimate test.

"IDOLiSH7 Third Beat!" maintains a balance between character-driven drama and the high-stakes world of idol performances, offering a compelling continuation of the IDOLiSH7 saga. The series explores the multifaceted nature of the characters' lives, providing a nuanced portrayal of their journey in the competitive and often unforgiving world of idols.