Episode 11 of "Yuzuki-san Chi no Yonkyoudai" focuses on Hayato Yuzuki, the eldest of the Yuzuki brothers, as he falls ill and how his younger brothers and their friends take care of him.

The episode begins with Uta, a family friend, excitedly sharing stories about a weekend trip to a hot spring with her mother. Meanwhile, Hayato starts feeling unwell and shows the first signs of a cold, which he initially ignores. By the next morning, Hayato's condition worsens, and he becomes unable to leave his bed. His brothers Minato, Mikoto, and Gakuto realize he has a fever and decide to take over the household chores, insisting that Hayato rest. Despite his reluctance, Hayato agrees to let them care for him. Minato and Mikoto take charge of the situation, and Minato accompanies Hayato to the hospital. The doctor diagnoses Hayato with a cold, prescribes fever-reducing medication, and advises him to rest and drink plenty of fluids. Minato enthusiastically takes on the role of caregiver, making sure Hayato follows the doctor's instructions.

At home, the brothers handle meals and household duties, showing their affection and concern for Hayato. However, Hayato's condition does not improve as expected, which worries his brothers.

In a moment of crisis, when Hayato's fever spikes, the Kirishima family, who have just returned from a trip, come to the rescue. Uta's mother, a police officer, takes Hayato to a doctor who works on weekends, while Kojiro and the children stay with the Yuzuki brothers.

The episode highlights the strong bonds within the Yuzuki family and their extended circle of friends.