In Erased, when Satoru got transported back to 1988, he mistakenly referred to his mother as "kaasan". However, when pointed out, he quickly switches to "okaasan". Why is that?

As far as I know people usually refer to their own mother as "kaasan", and not "okaasan" as Satoru did.

  • 2
    The initial o- (お-) prefix is an honorific prefix. It is used to show politeness to parents, but it’s not uncommon to hear “Kaasan” or “Tousan”. In more casual situations the speaker may omit this prefix. Oct 16, 2021 at 4:09
  • Pointed out what? Okaasan is quite common when talking to one's mother. I guess it is more common than kaasan.
    – sundowner
    Oct 17, 2021 at 23:01

1 Answer 1


I suppose you're referring to the following exchange (from here).

悟  :あっ・・・母さん・・・(Ma・・・)


悟  :えっ?お・・・お母さんって言ったでしょ?(I said "Mom.")

In Japanese, a large majority of kids call their mother either okaasan or mama, depending simply on the custom of each family (and switch very rarely). A kid ( <12 years old, say) saying kaasan is relatively rare, that is why it sounded weird to the mother.

So Satoru apparently switched from okaasan to kaasan at some point when he grew older. He first used kaasan due to his 'current' (i.e., as a grown-up) habit, but it sounds unusual to the mother, then he 'corrected' it to okaasan, which should have been the way he called his mother.

If I remember correctly, Conan (or Shinichi) the detective called his mother kaasan, but he is 15 or 16 years old. As people grow older, use of kaasan becomes more common, while it is by no means strange that a 50-year-old man calls to his mother by okaasan.

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