Have you tried HideMyAss? They offer both VPN and proxy services, and their Japan servers are pretty reliable. I’ve used their japan web proxy for light browsing, and it’s been stable for me.
It’s not free, but the price is reasonable, and they have a decent refund policy if it doesn’t work out for you.
It’s not free, but the price is reasonable, and they have a decent refund policy if it doesn’t work out for you.