Summary
If you make 2,186,400 円 a year living in Japan, you will be taxed 412,344 円. That means that your net pay will be 1,774,056 円 per year, or 147,838 円 per month. Your average tax rate is 18.9% and your marginal tax rate is 20.9%. 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 20.85 円, hence, your net pay will only increase by 79.15 円.
Bonus Example
A 1,000 円 bonus will generate an extra 792 円 of net incomes. A 5,000 円 bonus will generate an extra 3,958 円 of net incomes.