There are one direct and indirect flights connecting Southampton and Tokyo every week, with the journey taking 22 hrs 35 mins on average.
Or, if you're fairly flexible on dates, try to get a last minute-deal by regularly checking the Netflights website.
Tokyo actually has one airports to choose from – but Tokyo Haneda International Airport (HND) is the usually the cheapest option. If you need to fly into a specific airport, adjust your search to focus on those flights. The most popular airlines include Lufthansa.
If you can’t find flights that suit you, consider flying to a another part of Japan.