Summary
If you make 37,277,856 円 a year living in Japan, you will be taxed 13,343,446 円. That means that your net pay will be 23,934,410 円 per year, or 1,994,534 円 per month. Your average tax rate is 35.8% and your marginal tax rate is 41.0%. This marginal tax rate means that your immediate additional income will be taxed at this rate. For instance, an increase of 100 円 in your salary will be taxed 41.02 円, hence, your net pay will only increase by 58.98 円.
Bonus Example
A 1,000 円 bonus will generate an extra 590 円 of net incomes. A 5,000 円 bonus will generate an extra 2,949 円 of net incomes.