I would like to know about the Small and Medium Enterprise Retirement Allowance Mutual Aid Premium Subsidy System.

There is no city subsidy.
There is a system in which the government subsidizes a portion of the premiums for businesses that participate in the Small and Medium Enterprise Retirement Allowance System.
For details, please refer to the page of "Q&A 1. Overview of the system" on the "SME Retirement Allowance Mutual Aid Business Headquarters" website .