Kei Komada is the older brother of Rui Komada, the young president of the Komada Distillery. Born into the Komada family, he was initially positioned to inherit the family business. However, following a major earthquake that damaged the distillery's equipment and halted the production of its signature whisky, Koma, a significant disagreement arose between Kei and his father over the management and future direction of the company. This conflict led to Kei leaving the family distillery, effectively severing his path as the heir apparent. He subsequently began working for a rival company, the樱森造酒厂 (Sakuramori Distillery).

In the story, Kei functions as a secondary but crucial character who represents a direct challenge to the protagonist, his younger sister Rui. While Rui has given up her personal dreams to revive the family's Koma whisky and restore the distillery, Kei takes the opposite stance. He is portrayed as estranged from the family business and actively pressures Rui to sell the Komada Distillery to the rival company he now works for. His motivations are rooted in the same deep passion for whisky that drives his sister, but this shared passion led them to irreconcilable conclusions about the distillery's future following the disaster that crippled it. Kei's departure from the family is not born of simple indifference but from a fundamental disagreement on policy and recovery strategy, which fractured the family bonds that the Koma whisky was meant to represent.

The central conflict between Kei and Rui forms a core part of the film's drama. Kei's role is to act as a foil to his sister's determined effort to rebuild. His stance forces Rui to confront the painful family history and defend her choices, while his own perspective on the failure of the old guard's methods provides insight into the difficult decisions that followed the earthquake. While Rui is focused on the past and the restoration of a lost legacy, Kei's path represents a more pragmatic, though equally passionate, break from that same legacy. Despite their opposition, the narrative explores how both siblings' actions are driven by their relationship to their family's history and whisky. Kei is a skilled professional in the whisky industry, possessing the knowledge and experience to work at a competing distillery, which makes his opposition to Rui a credible and serious threat. His choices and the backstory explaining them are key to understanding the rift at the heart of the Komada family and the high stakes of Rui's mission.