Secondary mobile SIM card?

[tlyjmv]

Considering getting a secondary mobile SIM card with a separate number from one of the cheaper providers, to keep private and public apart. I'm ok with them scanning my ID when I pick it up (as seems to be required?) but I'm a bit concerned with receiving bills/letters/advertisement to my home address (resident in Japan).
Anyone in a similar situation? Any advise?

 

[impish]

This is why I went with a skype 050 number for public stuff. No adverts.

 

[Sudsy]

I have an IIJMIO sim for my tablet. I have never seen physical mail from them, not even once.

 

[tlyjmv]

For tablet, so data only then?

Reading through their site though, it seems kind of obvious I need to find something that's either amazingly easy to sign up for or offers service in English. I forgot how much paperwork there was to sign up for my primary mobile plan...