The Airline Expo in Japan is described as an event "by airplane lovers, for airplane lovers", and the inaugural event was held in 2016. The two-day affair is held in collaboration with various airlines and other businesses that support the aviation industry, and includes booths from domestic and international air carriers, airline-related goods for sale, stage events, and plenty more.
There is no admission fee to browse the event, but do bring yen if you plan on making a purchase.