普通形と です・ます、どっち？ (futsuukei to desu-masu, docchi?) — Who gets which

Grammar rule (व्याकरण नियम र परिभाषा)

This is the most important page in the lesson. The line falls like this. **Always です／ます:** your 店長, 課長, 部長, any 先輩, customers, and anyone you met today. **Plain form is fine:** friends, 同僚 of your own age and rank, and 後輩 who joined after you — but only once they have used plain form with you first. **Three rules to remember. One:** let the other person switch to plain form first, then match them; do not start it yourself. **Two:** even when a 先輩 says 「休み？」to you, you answer 「はい、休みです」— it runs one way only, and this is the part most Nepali workers get wrong. **Three:** in Japan a 先輩 is made by joining date, not age — someone two years younger than you is still your 先輩 if they started first. **⚠️ When in doubt, です／ます:** nobody is ever offended by polite speech, while plain form in the wrong place sounds rude. The かい, じゃないか, かな and さすが in this lesson are for understanding, not for speaking — but 〜て よかったです and 〜て すみません you can use with anyone, starting today.