Nagisa Oshima is 79 years old (birthdate: March 31, 1932).
Michiru Oshima is 50 years old (birthdate: March 16, 1961).
Yumiko Ōshima is 64 years old (birthdate: August 31, 1947).
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There is no clear answer, some youngins are old and some oldins are young. Another opinion: At least 80. On the lighter side. This answer was kindly dedicated to Lazarus