Why does the same person speak so differently to a boss, a client, and a friend?
Japanese has grammatical politeness (keigo): plain form with friends, polite -masu/-desu with acquaintances, and honorific/humble forms (sonkeigo/kenjougo) that raise the listener while lowering yourself. Speakers switch mid-conversation as the audience changes.
Keigo is a built-in linguistic system for marking relationship and distance, not just 'being polite.' The form you choose broadcasts how you rank the relationship and which group (uchi/soto) the listener belongs to.
Why — five layers
Positioning self and other correctly (lowering oneself, elevating the listener) is a core courtesy; using plain form with a superior can read as disrespect even if the words are kind.
Uchi-soto shapes usage: you use humble forms for your own in-group (your company) when speaking to outsiders, so keigo tracks group membership, not just the individual in front of you.
Schools teach keigo, companies run keigo training for new hires, and manners books standardize 'correct' business phrases (e.g., otsukaresama), institutionalizing it as a hireable skill.
International view
English marks politeness with word choice and modality ('Could you possibly...') but has no grammatical honorific system; Korean has a comparably rich honorific system, so Korean learners find keigo more intuitive than English speakers do.
But not always
Many native speakers also struggle with keigo and make mistakes; over-formal keigo can sound cold or sarcastic, and among friends switching to keigo suddenly can signal you're angry or creating distance.
What to do
As a learner, master -masu/-desu polite form first—it's safe almost everywhere and rarely offends. Reserve full sonkeigo/kenjougo for work; nobody expects a foreigner to nail humble forms, and effort is credited generously.
Sources
- linguistics of Japanese honorifics (sonkeigo/kenjougo/teineigo)
- corporate new-hire training practice
- general testimony