Wow! Very Appreciated for your detailed comments and suggestions.
I'm pleased to know someone treat my game this seriously, also willing to share your thought to me.
I will look into the problem you have mentioned.
The price of the items, rents and salary were set as close as real life Tokyo, I guess that's mean the life of a poor part-time worker is very hard.
I didn't set the difficulty on purpose, but I will sure adjust the number setting later.