She can come to France/ Ireland as a tourist, and maybe, send her belongings directly to you. You can visit her for short breaks/long weekends till the 1st Oct. She needs to enter UK after/on 1st Oct, but that doesn't mean that she can't travel out of Japan before that. Hope this helps.

"Currently a parent or grandparent can come to the UK to settle if they are aged 65 or over,...in particular at whether the relative aged 65 or over is necessarily 'dependent' on the UK-based sponsor... for example by being sent money by their relative in the UK. This change if implemented is highly ...