Sasurai-kun begins as a lonely, existentially dissatisfied salaryman, overworked in his corporate life and nursing an unexpressed affection for a female coworker sparked by her daily kindness. His life shifts dramatically during a commuter train encounter with the enigmatic salesman Fukuzou Moguro, who magically transports him to a rural hot-spring village, severing his established routine. Initially stranded, he resourcefully integrates himself into a group of businessmen to secure lodging and food, marking his entry into transient living.

His transition from office life to perpetual wandering completes rapidly after the first two episodes. Following a nightmare about his former job, he fully embraces his reality as a drifter. The narrative thereafter ceases referencing his abandoned career or financial constraints, implicitly presenting him as independently wealthy and free to roam rural Japan indefinitely.

Episodic encounters define his persistent search for connection. Early wanderings involve repeated attempts at romantic companionship, including a misguided pursuit of a high school girl reminiscent of a youthful infatuation, leading to socially awkward situations like drinking with teenagers. A subsequent, brief effort to join a Buddhist monastery reflects his struggle for inner peace and a failed attempt to suppress his desires.

Interactions with fellow societal dropouts, such as a former salaryman living primitively in the wilderness, highlight themes of alienation and alternative lifestyles, though Sasurai-kun continues his rootless path. Episodes increasingly emphasize solitude and melancholy, depicting him frequenting izakayas, reflecting on missed opportunities, and confronting the fleeting nature of human bonds. Recurring nightmares about isolation within impersonal, transient relationships reinforce his underlying anxieties despite his nomadic freedom.

Moments of warmth emerge through spontaneous integration into communities. He joins farm tourism groups, participates in local activities like refereeing children's baseball games, and experiences temporary familial acceptance. In one instance, a child recognizes his homelessness and invites him home, leading to a night of shared dinner and sake with the boy's family. This evokes a dream of his mother, prompting a silent dawn departure to avoid burdening them, underscoring his ingrained transience and unresolved longing for belonging.

His travels showcase distinct elements of Japanese culture and nostalgia, including interactions with sento bathhouse enthusiasts. A quest for an authentic view of Mount Fuji instead leads him through various baths featuring painted murals, culminating in an ironic encounter where a companion prioritizes artistic appreciation over natural scenery, mirroring Sasurai-kun's own often-misaligned expectations.

Throughout his wanderings, he maintains a fundamentally good-natured and adaptable personality. He navigates diverse situations—riding with an inexperienced driver on mountain roads, accompanying a nature photographer with differing intentions, or enduring a demanding tour of bathhouses—with passive resilience and mild humor. Despite the episodic nature of his experiences, a core loneliness and quiet yearning for connection persist.