The character of the Drunken Old Man in Densha Otoko, known in the live-action television series as simply the Drunk and portrayed by actor Ren Ōzuki, serves as the crucial catalyst for the entire story. He is an elderly, intoxicated passenger on a train in Tokyo who behaves in a loud, aggressive, and socially disruptive manner. His actions are explicitly obnoxious and lecherous; he is seen yelling at random, slapping passengers with a rolled-up paper, and making crude sexual remarks, such as propositioning a woman to touch him to feel his manhood. His behavior represents a clear and public threat in a setting where bystanders typically remain passive and avoid confrontation.

The primary role of the Drunken Old Man is to initiate the plot of Densha Otoko. As he harasses a young woman who would later become known as Hermes, he creates a situation where the shy and introverted protagonist, the Train Man, is forced to act. When everyone else on the train ignores the escalating incident, the protagonist must overcome his profound social anxiety and timidity to stand up and tell the old man to stop. The drunkard then physically attacks the protagonist, leading to a brief scuffle that ends when a stronger salaryman intervenes and subdues him. The Drunken Old Man is subsequently taken into custody by train staff, and his removal from the scene allows the protagonist and Hermes to interact for the first time, setting the romance in motion.

Regarding the character's background, the search results offer no information. His personal history, life outside of this train incident, and motivations are not explored within the narrative. He appears solely as an antagonistic force of public disorder with no redeeming qualities or sympathetic backstory. He has no key relationships with other characters, as he is a stranger who briefly disrupts their lives, and the character undergoes no development across the story. His only notable ability is his capacity to be a public nuisance, leveraging the common societal reluctance to intervene in uncomfortable situations. In a notable variation, one manga adaptation of Densha Otoko changes the character's target from the beautiful young Hermes to a matronly older woman, altering the dynamic of the rescue but preserving his function as the instigating drunkard. For the animated anime adaptation specifically, no information about this character exists in the search results.