Yuzuki-san Chi no Yonkyoudai.

Two years after their parents' sudden death, the four brothers of the Yuzuki family have grown used to living together and the loneliness that comes with their situation. The eldest of them, Hayato, has already taken up any and all family responsibilities at 23 years old. The second eldest, Mikoto, manages to calmly pick up the slack of both Hayato and his immediate younger brother Minato, who feels deep insecurities for being just 11 months younger. The youngest, Gakuto, seems to be wise beyond his few years. They may not always get along due to each of the brothers' distinct personalities, but they can always count on one another in both the joyful and bitter moments of their lives. (Source: MyAnimeList)