As the name implies, government bonds are the bonds issued by the government, which is responsible for interest and principal payments.
Interest is paid every six months, and principal payments are secured at maturity.
With regard to discount government bonds, September 2000 marked the final issuance of 5-year discount bonds with no further plans for reissuance. The remaining type of 3-year discount bonds, however, continue to be issued every other month. The chart below should give you some idea about the purchase price of a government bond. Newly-issued bonds are usually issued on the 20th of each issuing month, or the nearest business day after the 20th when that happens to be a bank holiday. At post offices, while the maruyu program is not applied, you can still benefit from the special maruyu program up to 3.5 million yen counting also the government bonds purchased at other financial institutions.