Retirement tax questions

You can enter the Japanese pension under Miscellaneous income:

1. Open or continue your return
2. Click on Show more next to Less Common Income under Income & Expenses section
3. Click Start/Revisit next to Miscellaneous Income, 1099-A, 1099-C
4. Click on Start/Revisit next to Other reportable income
5. On the next screen that says Any Other Taxable Income?, select Yes and Continue
6. On the next screen, enter "Japanese Pension" as the Description and enter the amount   
7. Continue and Done.

But before you do, read the treaty between Japan and U.S. first.