There is public assistance system as a part of social welfare.
It contains mainly monetary supports to the families struggling with poverty for making ends meet. Many of them are caused by loss of breadwinner due to traffic accidents, diseases and job dismissal.
Although this system is a right granted by the Constitution of Japan, the required conditions of receiving this support are working to the best of your ability and tap into any assets you may have.
In addition, if you choose to apply for it, you must submit the certificate of your yearly income.