After her father, the beloved town doctor, passes away unexpectedly, young nurse Baba Asuka desperately searches for a replacement to keep the struggling Baba Clinic open. Her prayers seem answered when Tsuruta Masayoshi, a brilliant physician who vanished from the community twelve years earlier under mysterious circumstances, suddenly returns. Without warning, he purchases the clinic and installs himself as its new director, his motives unclear and his demeanor a far cry from the man Asuka once knew. Now nicknamed Dr. Jumbo for his imposing and unconventional appearance, this gruff, ill-tempered doctor clashes constantly with Asuka, the late director’s daughter. Yet despite his abrasive personality and the cloud of suspicion surrounding his return, his extraordinary surgical skill and diagnostic genius cannot be denied, as he repeatedly saves the lives of patients in their small Japanese town.

The drama unfolds at the Baba Clinic, a small local practice now under the intense pressure of a larger rival, the Shirane General Hospital, which is led by the cold and calculating Dr. Tenryuu. The central dynamic is the antagonistic partnership between Dr. Jumbo and the determined but often overwhelmed Nurse Asuka, who fights to uphold her father’s legacy while trying to understand the man who has taken his place. Throughout the summer season, the series explores a series of medical cases, each forcing Jumbo to confront difficult diagnoses ranging from a young boy’s suicide attempt and a pregnant woman’s rare endocrine tumor to a musician’s terminal stomach cancer.

The narrative is driven by several notable arcs. A major threat emerges when the rival Tenryuu, who shares a dark and violent history with Jumbo, becomes embroiled in a scheme to destroy the Baba Clinic. In a key arc, Tenryuu’s younger brother, Kurahashi, feigns a romantic relationship with Asuka to infiltrate the clinic as a spy, leading to an emotional confrontation when his betrayal is exposed. This family conflict escalates to a medical board hearing where Kurahashi attempts to use falsified evidence to strip Jumbo of his license. The season reaches its climax with a life-or-death case as a patient, Kurahashi, deteriorates and requires an immediate living-donor liver transplant. Only his bitter brother Tenryuu is a match, forcing a final, tense resolution to their long-standing feud and testing the limits of Dr. Jumbo’s skills and his role as the town’s doctor.