Honma Chosuke is a significant supporting character who works alongside the protagonist, Shizuku Kanzaki, in the wine department of a Japanese beer company. Of humble beginnings, Honma lost both of his parents, a hardship that led him to pour his passion and soul into the world of wine. His deep devotion is so pronounced that his small apartment has become primarily dedicated to storing his extensive personal wine collection.

Honma is a hardcore wine enthusiast, but his preferences are highly specific and shaped by a past romantic disappointment. After being dumped by a French woman, he developed a strong aversion to French wines and became a fierce and knowledgeable proponent of Italian wines, specializing deeply in that category. This expertise earned him the nickname the "Italian Monster".

In his role within the company, Honma is a colleague of Shizuku, and their relationship evolves significantly over time. Initially, the two clash, likely due to differing personalities or approaches to wine. However, this early friction gives way to a strong friendship. Honma becomes a reliable and older brotherly figure to Shizuku, looking after the younger members of the team and proving himself to be a loyal and eager ally. He plays a supportive role in Shizuku's quest to find the legendary "Drops of God" wines, always ready to assist his friend in the high-stakes competition.

Honma is not a static character. He demonstrates personal growth, particularly regarding his own emotional past. A notable example occurs when he learns of his former French girlfriend's marriage. To process three years' worth of unresolved and conflicting emotions, he channels this intense energy into a single, meaningful bottle of wine, distilling his feelings into a potent personal expression. This act highlights his profound ability to connect deep human emotion with the art and experience of wine. Besides his encyclopedic knowledge of Italian wines, his most notable ability is this form of passionate, almost alchemical, dedication that transforms personal history into a tangible creation.