The Kyushu Area
The Southern tip of Japan, the area has many unique geologically and with the types of airports. I’ll go through a few notable airports briefly.
Fukuoka - The financial hub for Kyushu. It may not be in its glory anymore, but back in the day they flew to destinations like Amsterdam, London, and Portland, and many more (Unfortunately, most of the information is in Japanese, so you might need me for this research). But now, there is one seasonal flight to Helsinki. Even then, this airport is great to fly to islands like Tsushima and Goto.. It also has flights to most East Asian countries. Additionally, the airport is served by the JAL A350 so that would also be great.
Nagasaki - This Airport is not well known, but it is the world’s first fully-functional artificial island airport. It’s unique, and the airport is surrounded by a bay so you could look at a glorious scenery from every direction. It is also good for island hopping.
Kitakyushu - Short note for also being built on artificial island. Hub for StarFlyer (Not un game) but has JAL flights to Tokyo.
Kagoshima - It has wonderful scenery of Sakura Jima if you travel south.