Agree with that branch off. Don't confuse good design with symmetry or balance with equal foliage on either side of the trunk. There is a place for balanced, upright styles but also a place for dynamic leaning and windswept styles.
It may take some time to get used to such a dynamic design but it will certainly stand out from all the other 'balanced' trees at a show
Currently with that branch crossing others to provide the left side does not look good. Far better gone just for that reason alone but I think the trunk and branches will support the leaning style really well.
As mentioned earlier that's not the only bit I would like to remove. That whole branch could go and still leave a great bonsai.
I was told from the seller that it was an old import from Japan and estimated at 40 yrs old! But who knows!
There is every possibility that info is correct by the look of the trunk and branches. I forgot it is possible to import trees from Japan over there. Much more difficult for us down under. Some of the azaleas I collect from gardens are around the same age and size.
If it is already well established in the pot you could start work this year.