What the word literally means

The word is written with two kanji: "before" and "companion." Put together: "the one who was here before me." You'll see it spelled two ways — "senpai" and "sempai" — and both are correct: the Japanese "n" before a "p" sounds almost like an "m," hence the mix.

The key thing to understand: it's about seniority, not birthdays. A twenty-year-old new hire at a factory is the kohai of an eighteen-year-old who's already worked there two years. A college junior who joins the kendo club in their third year is the kohai of a sophomore who's been there since freshman year.

How it works in Japan

For Japanese people this isn't just vocabulary — it's a relationship system with its own rules. Each side has obligations.

  • SenpaiTeaches the newcomer how things work, gives tips on dealing with the bosses, covers for them if they mess up. Often picks up the tab for dinner after work — that's part of the role too.
  • KohaiPolite, listens to advice, doesn't argue with the senior in front of others, helps with small tasks. In return, gets experience and protection.

You usually address a senpai by last name plus the title: "Tanaka-senpai." It doesn't work the other way around: nobody calls a kohai that — they're just called by last name or with a polite "-kun" or "-san." The bond lasts for years: a former kohai might keep calling someone senpai long after that person left the club.