When we buy cell, ①Combined sale（Japan Basic）-->cell＋carrier contract needed. ②Sim-free（World Basic）--> Basically,New one.but don't need carrier contact (EX.two-year contract). ③白ロム(Shiro-rom)---＞Used.and don't need carrier contact (EX.two-year contract). ④赤ロム（Aka-rom）---＞Used include having an outstanding debt（WARNING）
It's necessary for tourists to get 白ロム(Shiro-rom).but you have to seek for it Akihabara or Amazon.If you need iPhone, Apple store sell Sim-Free one.