Many Japanese people are now nostalgic for the 1970s and ’80s, when the economy was booming and the culture had an exciting vitality and creativity. Think Pac-Man, Walkman and the “Sasori” action series starring Meiko Kaji as a fierce-eyed female prisoner out for vengeance against an evil patriarchy.But as Taichi Kimura shows so rousingly and entertainingly in “Fujiko,” his dramedy about a striving single mom, the era was hardly an easy one for women.Though the women’s liberation movement was then on the rise — the scrappy title protagonist (Yuki Katayama) even takes part in a raucous all-woman demonstration — male chauvinists viewed a stubbornly independent woman like Fujiko with alarm and disdain.