According to Japanese film critic and historian Tadao Satô, in casting this film about a schoolteacher and her relationships with her pupils over many years, director Keisuke Kinoshita very cleverly chose pairs of look-alike siblings to portray the students. So for those scenes set in later years, Kinoshita simply substituted the older siblings for the younger ones, so that the schoolchildren appeared to "grow" before the audience's eyes.
This film is part of the Criterion Collection, spine #442.