More interestingly, they announced an extremely inexpensive option for tethering any wifi device to a cellular network, the Hikari Portable 3G router. The Hikari Portable will be offered from June for a 300 yen per month rental fee to subscribers of NTT East's Flet's internet services, which includes Hikari Next and B Flet's.
Actually, with the cradle that includes both a 10/100 Mbps LAN and WAN port, this is a standard wireless router for home use. Unplugged and on the road, like the B-Mobile wifi, it becomes a 3G router. You must supply your own data SIM.
According to the FAQ, there will be two versions, one that is SIM lock free and one that is locked to NTT Docomo's network. Hmmm... I (sarcastically) wonder which one will be usable on Docomo? Presumably, B-Mobile's 300 Kbps product is the only current option for the SIM lock free version.
Q:「光ポータブル」はSIMロックですか、SIMロックフリーですか？It also has a micro SD slot (up to 32 GB), and mini USB port. Sans cradle, it is just under 4 inches long, about 2.5 inches wide, and weighs 105 grams. Battery life is listed at 6 hours (30 hours standby). See tech specs (Japanese).
Unlike the B-Mobile wifi, however, it can be rented for a nominal monthly fee. For someone who is dead set on getting a 3G router, this is, all in all, the best option for people in the NTT East service area.
Not only does it double as a home wifi router, but the LTE roll out is coming, after which 3G equipment will be obsolete. Even if it takes 2 years from now before LTE is widely available, compare the cost of purchasing B-Mobile's 3G router to the cost of renting for 2 years the Hikari Portable: 19,800 yen for buying 3G equipment versus 7,200 yen (7,560 yen including tax) in rental fees.
If you live in the Kanto region and find this compelling but are unfortunately subscribed to Yahoo BB, see my rambling rant on how to avoid their "落ちる穴", which was added to the cancellation terms in 2008 with the sole purpose of squeezing more money out of customers who got fed up with their consistently high latency and decided to switch ISPs. (I was located less than 1 Km from an ADSL base station but always, no matter what time of day, had about 150 - 200 ms latency which resulted in timeouts when initiating multiple connections at once, even though my download speed was always in excess of 30 Mbps.