Yuzuki-san Chi no Yon Kyoudai.

The Yuzuki brothers, consisting of the eldest son, Hayato; the second son, Mikoto; the third son, Minato; and the youngest, Gakuto, have been living together since they lost their parents two years ago.

Minato and Mikoto are barely a year apart in age, which means they study together, and Mikoto has always been considered the older one. Why did his younger brother take everything from him at birth? Is there any resentment between these two brothers? What does it mean to be an older brother?

Gakuto spends a lot of time with the Kirishimas, but it wasn't always this way. Shortly after their parents' deaths, Hayato tried to handle everything on his own, running home from university every day to be there when Gakuto came home from kindergarten. One day, he noticed Kirishima-san's grim looks.

Hayato is looking forward to his class reunion. But his former classmates complain about work and brag about their travels, while he only talks about his brothers. He feels left behind by life...

Uta and Minato are best friends. One day, a classmate declares his love for Uta. The two arrange a date. How will Minato react?

Minato no longer knows how to deal with Uta. Uta, for her part, isn't approaching Minato like she usually does. What will become of their friendship and Uta's relationship?

Minato first met his best friend Uta when they were elementary school students. Uta, who moved next to the Yuzuki family, responded coldly to Minato and Mikoto. Determined to become friends with Uta no matter what, Minato enthusiastically keeps inviting them to play, but...

A class observation day was scheduled to be held in Gaku's class. However, Gaku was worried that if Hayato took a day off to attend, it would cause inconvenience at his workplace and increase his workload.

Gakuto is keeping his class observation day from Hayato by using a stand-in.

The Yuzuki family's four brothers cherish each other deeply. Among them, the second son, Mikoto, dotes on Minato, the third son, while Minato, in turn, adores Gakuto, the youngest.

Hayato catches a cold. Mikoto, Minato, and Gakuto are eager to care for Hayato and handle the household chores. Even when they run into the Kirishima family on their way to a trip, they keep Hayato's condition a secret, not wanting to worry them before their vacation.

Gakuto won a diary. Wondering what to write as the entry, Mikoto mentions, "You can also write about your thoughts and feelings." Encouraged by this, Gakuto chronicles the daily happenings in the Yuzuki household...