Cheap Sim Card only for calls

Hello everybody. I am going to Japan for about 20 days. I need a sim card for making few calls. I do not need internet access or 3G etc.
Do i need to rent one. If yes than what is the cheapest way this can be done ? I really only need to make calls.

I think you can get prepaid SIM cards in some big stores like Yodabashi Camera.
Look for b-mobile they have some prepaid offers. I'm not 100% sure they have one with only calls and no internet but they have some things with a phone number and it's not too expensive, maybe around 3000 for 15 days or one month (not sure about that)

Prepaid Voice SIMs cannot be purchased by non-residents. You can rent them from companies such as Softbank, JCR or Cellhire but you need to have a 3G compatible phone which supports the 2100 UMTS/HSPA.

The only place that seems to consistently sell Prepaid Voice SIMs to non-residents is at Softbank Roppongi.

Do i need to rent one. If yes than what is the cheapest way this can be done ? I really only need to make calls.

It may be cheapest to get one of the rental sims that don't have a rental charge and only bill you for the calls made. Their per minute charges tend to be expensive (2x the typical fees), but it may pay off depending on how long you need to have it. Here's one available at Narita Airport:

https://www.mobalnarita.com/