activation problem need help
 

IMEI: 012533002972012
Serial Number: 860431LFA4S
Model: IPHONE 4 16GB BLACK
Warranty: Out of Warranty
Activation Status : Yes
Last Active SIM: SoftBank - Japan JPN
Locked by Carrier: Japan SoftBank
SIM Lock: Locked

this is iphone 4 softbank with IOS 7 but i cant activate with softbank sim its say

The SIM card inserted in this iPhone does not appear to be supported.

pls if any one know what is this isue help me o activate it.