55 When a pension plan is transferred to a new system such as defined-contribution pensions, it is necessary to protect, on the basis of labor-management negotiations, the retirement benefit debts, i.e., the right to receive benefits, which are the vested interests of subscribers and recipients. For this reason, it should be noted that the very existence of retirement benefit debts impedes the smooth transfer of pension systems, as seen in the large number of instances, particularly among small and medium enterprises, where the existing pension system is maintained as is.