With the big carriers here you pay 0.05yen per packet, where a packet is 128 bytes. For example, looking at my bill from March, I used 6,971,294 packets (0.84GB) which would have cost me a grand total of 348,564yen (~$3000). I "only" paid 5200yen (~$50) for it because I'm signed up for a fixed data plan like everyone else. The exorbitant base prices are only there to make sure that everyone signs up for the expensive plans without too many complaints.
Oh, and did I say that all three big carriers have the exact same prices with more or less the exact same plans? :)
I bought a data-only SIM to use in Japan, there were a few to choose from, prices were around £25 for a gig of data. Oddly that's actually cheaper than your plan!
Pretty obvious I never used their data services abroad, but being offline when traveling is actually a big plus for me.
(just to explain, it's one of very few pay-as-you-go operators @ Suisse, for people like me who don't use their smartphones that much and have offline maps for navigation)
If you happen to be roaming abroad, they have data plans for 10 days / 100MB for 15 CHF, which is not great, but way cheaper than the example you gave above.
In Italy (capped): Calls 18p/minute, data 19p/MB
In Japan (unregulated): Calls 149p/minute, data 800p/MB
Data is over 40x as expensive ! The pricing that telecoms companies charge when they can are obscene. (The capped 19p/MB is still vastly overpriced IMO as well...)