Formal — to staff
Shinkansen · Seat
You
すみません、後ろのテーブル使われてますよね？少しだけシートを倒してもご迷惑じゃないですか？
すみません、うしろのてーぶるつかわれてますよね？すこしだけしーとをたおしてもごめいわくじゃないですか？
Excuse me, I see you are using the table behind me. Would it bother you if I reclined my seat just a little?
Romaji: Sumimasen, ushiro no tēburu tsukawaretemasu yo ne? Sukoshi dake shīto o taoshite mo go-meiwaku janai desu ka? / Reply Romaji: A, zenzen daijōbu desu yo! Dōzo, taoshite kudasai.
Reply
あ、全然大丈夫ですよ！どうぞ、倒してください。
あ、ぜんぜんだいじょうぶですよ！どうぞ、たおしてください。
Oh, that's completely fine! Go ahead and recline it.
Gesture & etiquette
Turn around slightly to make eye contact, and bow your head lightly while gesturing to your seatback.
Do not recline your seat suddenly without checking, especially when the person behind you has hot drinks or a laptop on their tray table.