Nobody Knows 2004 (Japan), also known as Dare mo Shiranai is Japan drama premiere on Aug 7, 2004
Nobody Knows tells the story of four siblings and their young mother (played by J-Pop star You) who move into a small apartment in Tokyo. There is no father around, and in fact, all the children are the offspring of different men, as a result of their mother's wild lifestyle and immature personality. Yet, in the beginning, the family life is portrayed in a lovingly chaotic way. Society might not give the seal of approval, but the members of this non-nuclear family seem to enjoy an adventurous life together.
Things change for the children (12-year-old Akira, his serious-minded younger sister Kyoko, and their two younger siblings: avidly curious Shigeru and the adorable and innocent Yuki) when, shortly after they move in to their new home, their mother leaves to begin a new life with a man who lives in Osaka. Left with only a small amount of money and a note asking Akira to look after his younger siblings, the eldest brother's rank in the family shifts overnight and he becomes the surrogate head of the family.