"Coffee Samurai" is set in a fictionalized version of Edo-period Japan, blending historical elements with fantastical twists. The narrative centers on Haruto, a young samurai who inherits his family’s traditional coffee shop after his father’s untimely death. The shop, named "Kohi-ya," is no ordinary establishment; it serves as a front for a secret order of warriors tasked with protecting the realm from supernatural threats. These threats manifest as shadowy entities known as "Kurogami," which feed on human despair and are drawn to the aroma of coffee, making the shop a battleground.

Haruto, initially reluctant to embrace his dual role as a barista and a warrior, is guided by his late father’s spirit, who appears in visions to impart wisdom and combat techniques. Alongside him is Aoi, a skilled kunoichi (female ninja) and childhood friend, who assists in both running the shop and fighting the Kurogami. Their dynamic is marked by a mix of camaraderie and tension, as Aoi often challenges Haruto’s indecisiveness and lack of confidence. The duo is later joined by Ren, a mysterious traveler with a deep knowledge of the Kurogami and their origins, who becomes a key ally in their mission.

The plot unfolds episodically, with each episode featuring a new Kurogami threat tied to a specific historical or cultural element of Edo Japan. These encounters often reveal deeper layers of the characters’ pasts and motivations. For instance, one episode explores Aoi’s struggle with her clan’s expectations, while another delves into Ren’s tragic connection to the Kurogami. The series also incorporates themes of tradition versus modernity, as Haruto experiments with new coffee brewing techniques, symbolizing his journey to balance his heritage with his individuality.

As the story progresses, the trio uncovers a conspiracy involving a powerful daimyo (feudal lord) who seeks to harness the Kurogami’s power for political gain. This revelation ties the episodic conflicts into a larger narrative arc, culminating in a climactic battle at the heart of Edo. The series concludes with Haruto fully embracing his role as both a protector and a pioneer, ensuring the legacy of Kohi-ya while forging a new path for himself and his companions. The blend of historical intrigue, supernatural action, and character-driven drama makes "Coffee Samurai" a distinctive entry in the anime genre.