It depends on the area and your lifestyle, but, for reference, the average cost of living is approximately \120,000 to ¥150,000 in Tokyo, ¥70,000 to ¥100,000 in Nagoya, and ¥80,000 to ¥110,000 in Kobe.
Reference for costs：A Big Mac set at McDonalds costs ¥690 and a tall late at Starbucks costs ¥380.