I agree with Zlatica that you probably starting at the wrong end. May I suggest. You say you have a record of her marrying in the British Consulate in Yokohama? Obviously husband was British - must be some record of where he came from, what he was doing etc. You say he and the children went to LA in 1923 - where were they between? Possibly back to England? If there is no record of her dying in LA she could have died in England. I think it might be worth following that trail but you will need to know at least where he came from - James is, unfortunately for you, a very common name, but not impossible to track.