Switching to a cheaper phone plan and keeping your number (MNP)

You usually don't need the shop at all to switch carriers. Since May 24, 2023, Japan has the MNP ワンストップ方式: if both your current and new carrier support it, you apply on the new carrier's website only, log in to your old carrier's My Page when it redirects you, and no MNP予約番号 is needed. The old contract ends automatically once the line switches. With the two-step method (ツーストップ), obtain an MNP reservation number from your current carrier. Check that carrier’s current conditions rather than assuming a phone or shop request costs 1,100 yen; for example, Docomo currently lists the MNP transfer fee as free. Also, the old carrier isn't allowed to push you to stay without your consent, and porting in costs nothing, though the new carrier may charge a 契約事務手数料 (contract admin fee).