QF files no fares between LON and TYO.

EK fares LON-TYO permit use of QF flights between LHR and DXB. e.g. an example routing table for a fairly cheap EK Y fare:

1. LON-EK/QF-DXB-EK-TYO
2. LON-EK/QF-DXB-EK/QF-BJS/BKK/CAN/DPS/HKG/HKT/JKT/KUL/MNL/
OSA/SEL/SGN/SHA/TYO-EK/QF-TYO
3. LON-EK/QF-DXB-EK/QF-TYO
4. LON-EK/QF-DXB-TYO

Caveat 1: just because the route is permitted, it doesn't mean a flight or codeshare is available.
Caveat 2: this would be an EK fare on an EK-issued ticket, which is outside my personal experience

Shame SIN isn't there; QF has codeshares on EK DXB-SIN and JL SIN-TYO.