Here's the synopsis found on the film's Eigapedia page:
Tomohiro brings his fiance Machiko to his hometown of Aridagawa, Wakayama to visit his parents' home. However, Tomohiro's family life is quite chaotic. His younger brother Takashi hasn't been attending school, his sister Yumi completely ignores the family, and his other sister Sayaka is afraid of relationships due to her inferiority complex.
Meanwhile, there's also a woman named Satomi whom everyone calls "Mama" in charge of all the housework, a beautiful snack bar manager named Kayoko who they call "Kaka", a high school teacher named Narumi who they call "Haha", and finally the father Shoichiro who's known as "Chichi".
In spite of their complicated living arrangement, they seem to manage to maintain some sense of balance. However, the arrival of Machiko causes a ripple effect throughout the family.
Neko ni Mikan opens in Japan on March 22, 2014. Watch the Japanese-language trailer below.