Why is -san sometimes, but not always, added to the end of Nakamura's name? (in Hiroshima)please please please help!! :)

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I can understand
why you might find this inconsistency in the use of -san confusing. The addition of the
suffix -san to a name is done as a sign of respect. The closest correlation I can think
of in English are titles such as Mr., Mrs., and Miss. You would not refer to your
teacher as Smith rather than Mrs. Smith. At the same time, you probably wouldn't refer
to your sister as Mrs. Smith, but you would likely call her by her first name. This is
why in Hiroshima we see Nakamura or Nakamurasan depending on who is speaking. Her
children or other friends might refer to her as Nakamura while someone on less familiar
terms might refer to her as Nakamurasan.

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