The Japan Pension Service (JPS) has been hinting about easing eligibility requirements for receiving the old-age pension for a few years. Lifelines first covered this issue way back in 2014 (bit.ly/lifelines10yrpension).
The change finally became effective from last month, when the fact was announced with little fanfare on the JPS website. Basically, you can now receive a Japanese old-age pension if you have paid in for a total of at least 10 years, rather than 25 years, as was the case.
This applies to both the national pension (kokumin nenkin) system, which covers everyone, and the employees' pension insurance (kōsei nenkin) system, which covers salaried employees.