Current tariff of China Eastern Airlines encourages to visit not that usual destination of travellers willing to visit Japan – Okinawa island. These are open-jaw air tickets, in this case it means you have to look for flights departing from Rome to Okinawa and returning back either to London (air tickets available for €455) or for a slightly higher rate to Frankfurt (€475)
In case of interest please look for travel dates till March 2014 (however I have managed to find the cheapest flights between November 2013 and March 2014, booking for this rate level is possible till 30th of September, the cheapest flights offers booking agentwww.ebookers.de or its offshoots or for slightly higher rate you may book via Expedia.
Travel dates: please look for departures on Tuesday, Thrusday, Friday or Saturday and return flights on Monday, Wednesday, Friday or Saturday.
There is a longer stop-over on the way in Shanghai which you may take the advantage of and visit the city as most of EU countries may obtain free transit visa on-arrival