Amazon has decided that offering 3G-capable Kindles isn't enough of an involvement in the cellular world -- it's now getting into the business of offering the bits themselves. Through a tie-up with NTT DoCoMo-using MVNO Japan Communications, Amazon is selling prepaid SIM cards for LTE data. Each slice of plastic and circuitry will provide a 500MB block of sweet, sweet 4G for ¥1,980 ($25). There's a very good chance we'd burn through that in a day, but it'll let you get an NTT DoCoMo-ready smartphone or Arrows Tab online in a pinch. The Japanese can snap up the cards later in the month, while those of us in the US will just have to hope that Amazon can make a similar (if hopefully cheaper) deal closer to home.