There are ways to spend a lot less money on your keitai service, but they tend to not be widely know in the international community.

http://www.mondaiji.com/blog/japan/general/10240-sim-only-mobile-providers-in-japan

www.bmobile.ne.jp

mvno.dmm.com

www.iijmio.jp

broadband.rakuten.co.jp/rmobile

join.biglobe.ne.jp/mobile/lte

www.freetel.jp

home.hi-ho.ne.jp/hihomobile/lte/d

service.ocn.ne.jp/mobile/one

umobile.jp

http://www.uqmobile.jp/en/

au reseller
mineo.jp

http://www.mvno-navi.com/mvno-calls-plan

ID you will need to have to get a phone (voice) account:
Driver’s license
Must be issued by the Public Safety Commission and valid (international driver’s licenses are not accepted)

Passport (Japanese)
Must be valid and contain your current address

Identification Booklet for the Physically Disabled, Treatment Booklet, Mental Disability Certificate
Must contain your address

Special Permanent Resident Certificate
Must be valid

Residence card
If the address is listed as “undecided (list on the reverse after submission)”, one of the supplementary documents listed below is required. “Temporary visitor” and “no residential status” card holders are not eligible to apply for service.

Health insurance card
Must be valid