I don't know specifics of your industry. However, salary levels are much lower here although cost of living is also cheaper but probably not in the same proportion.
Before leaving Tokyo my wife earned approximately US$40,000 in a financial services company. If she took the same position here she'd get less than S$40,000. There is your marker conversion. Most Japanese here talk about Yen100 = S$1.00.
Costs can generally be converted at that rate although there are some wide variations. Accomodation is definitely much cheaper here - around 50% cheaper but the quality is much inferior. Utilities are cheaper. I paid Yen40,000 per month in Tokyo while here I pay around S$250 per month.
If you look at general shopping - then fruit & veg is cheaper but (equivalent) clothes, general cleaning aids etc are the same/more expensive than Tokyo. Japanese products are VERY expensive - no discounts here. You can pay 3 times as much for some food items.
Some Japanese like it here and some do not. It's smaller and easier to get around, you'll be able to afford a bigger apartment and probably a maid whether that be full time or part time. It's easier to get to surrounding tourist areas and to play golf. On the downside, it just doesn't have the same variety, quality, range of excellent food or excitement as Tokyo.
