"K: Missing Kings" is a direct sequel to the original "K" anime series, continuing the story set in a world where seven powerful clans, each led by a King, wield extraordinary abilities. The narrative centers on the aftermath of the events in the original series, particularly the disappearance of Yashiro Isana, also known as Shiro, the former Silver King. His absence leaves a void in the balance of power among the clans, and the story explores the consequences of this disruption.

The plot begins with the Homra clan, led by Mikoto Suoh, the Red King, facing internal strife and external threats. Following Mikoto's death in the original series, Homra is left vulnerable, and its members struggle to maintain their unity. Meanwhile, the Blue Clan, Scepter 4, led by Reisi Munakata, continues to enforce order, but tensions rise as the clans' fragile equilibrium is further destabilized.

The story follows Kuroh Yatogami and Neko, two key characters from the original series, as they search for Shiro, who vanished after the climactic battle. Their journey leads them to uncover a conspiracy involving the Green Clan, Jungle, and its enigmatic leader, Nagare Hisui. Jungle's ambitions to overthrow the existing order and establish a new hierarchy threaten the stability of the entire world.

As the narrative progresses, Kuroh and Neko encounter Anna Kushina, a young girl with a deep connection to the Homra clan and the Red King's legacy. Anna's latent powers become crucial in the fight against Jungle's machinations. The story intertwines the fates of the clans, highlighting themes of loyalty, power, and the consequences of wielding authority.

The film also delves into the backstory of the Kings, particularly the relationship between Mikoto and Reisi, shedding light on their shared history and the ideological differences that define their conflict. The interplay between the clans' leaders and their subordinates underscores the complexity of their world, where alliances are fragile, and trust is often a liability.

"K: Missing Kings" builds on the foundation of the original series, expanding its lore and deepening the character dynamics. The film sets the stage for further developments in the "K" universe, leaving viewers with a sense of anticipation for the ongoing struggle among the clans and the unresolved mysteries surrounding Shiro's disappearance.