Seven years ago, the Kashiwagi couple were killed in a car accident. They left behind six children, who were forced to live in different families. However, after a career-ending injury, Tatsuya decides to reunite his brothers and sisters to live together under one roof. To his disappointment, he is met with resentment and discord.

Two years after the events of Season 1, Koume attends university and a "ban on luxury" is introduced in the Kashiwagi household. When Masaya goes to study in Germany, the Kashiwagis decide to take on a new resident. They live happily and sometimes fight, but then Koyuki is diagnosed with an aggressive form of leukemia. Will Koyuki be saved?