The seat: 36G, a window seat near the back.
Price: $145
Flight time: 1hr, 40m.
Fellow passengers: A mixture of business people and tourists, Japanese and international.
How full: Very full — I couldn't see an empty seat. I chose to fly from Sapporo to Tokyo because it takes eight hours by train. This is probably why so many people fly between the two cities, making Sapporo-Haneda one of the busiest air routes in the world.
Food and drink: The cabin crew served a selection of hot and cold drinks, including green tea, berry tea, mineral water, apple juice and coffee. Additional items available for purchase included beer, and rice and onion soup.
Entertainment: There were several music channels and news in Japanese, but no seat-back screens. This didn't really matter for a relatively short flight.
Service: The cabin crew were calm, smiling and efficient. The crew members I spoke to had adequate English.
Toilets: Spotlessly clean. A lavender sachet scented the air, a nice reminder of the Hokkaido summer.
Luggage: The allowance is one 20kg bag checked, and one 10kg carry on bag.
Final word: Air Do (say it like hairdo without the h) is one of several airlines flying this route, and I would happily fly with them again.