[Sangetsu]

The main requirement is a bachelors degree or better from an accredited university. The subject of your study is not important.

Insurance varies according to your employer, you'll have to pay into the national healthcare system, but it's not expensive, perhaps 10,000 per month. Some employers have additional plans which eliminate any personal costs, and they are cheap as well.

Pay is typically about 250,000 yen per month. Typical payroll reductions for rent, insurance, and such will give you a net income of about 200k yen per month. Gas and electric will set you back about 6000 yen, a cell phone will cost about 10000. Internet varies, it's usually about 5000 a month, or it may be included with the rent for your apartment.

Food and entertainment are usually the largest expenses. Stores, shops, bars, restaurants, theme parks, clubs, etc. These can range from 300 yen curry shops to places which charge 1000 yen for a garden variety beer.

200k will not go especially far in Tokyo, but you can live quite nicely on that amount in the countryside. I live more or less in the country, and have a brand new 2dk apartment near the school and the train station, the cost is only 60,000 per month. My gf's similarly-sized apartment in Tokyo runs almost 300,000 yen per month.