ANA availability is key.
I have done a mini research on the LAX-HND-LHR (and vice versa), and definitely, very slim pickings on the availability of ANA, especially HND-LHR.
Unless you are looking at last minute half-way-around-the-world-in-first-class, or book 8-12 months out, you will simply not get the availability to align for both legs.