Funny how it's theme is similar to Man Who Shot Liberty Valance
Both resolve themselves to convenient myth. One is to conceal shame, the other to avoid complication.
shareInteresting observation.
However, I'd say the lie at the heart of Liberty Valance ("When the legend becomes fact, print the legend") more than sparing shame to a single man, is intended to benefit the People and help create an idea of justice the country can build its foundations on. A Noble Lie if you will.
Whereas the lie at the end of Seppuku only serves the powers that be and helps maintain the status quo.