When I checked in at Narita on my way to New York, I realized that I’d been assigned a middle seat. Great. I guess that’s what you get when you book a ticket yourself rather than through a travel agent, I thought. I pressed the button to try and change it, but all the seats were full. Twenty minutes before my flight, I decided to try and ask one of the ladies at the gate – 空いている通路席(つうろせき)はありませんか。Are there any aisle seats available? Miraculously one was free. She tore up my old boarding pass and handed me a new one. Don’t ask me how it happened, I’m just glad I had the leg space and easy access to the bathroom. Maybe she was so surprised someone wasn’t asking for an upgrade to business class that she was happy to oblige me.
If you’re looking for a window seat, the word you want is 窓席(まどせき). I’m not sure why you would request a middle seat, but I believe the word is 中央席(ちゅうおうせき).