Currently I am using Tokio Nichido Marine (the one with the blue and yellow logo) They are charging me about 12,700 yen a month. Based on my Insurance rating (level 16 or so, no accidents in the last 5 years), I think they are a little high. I did an online quote with the SBI/Marche group and that come out to closer to 9000 yen per month. I am going to go talk to Mitsui Sumitomo and see if they have a better deal. I'll present all that to my current guy and see if I can get a better rate.
I have an acquaintance in Hiroshima who said they are paying about 9000yen a month, but I don't know which company they are using. They have an SR+, I have a LR Dual Motor.