Living expenses

Roughly how much would an single average person need to survive in japan ? Location( yokohama )
Apartment, electricity , phn,gas , water , etc

It depends.
How warm you like on winters or cold on summers. How much water you use on each bath, or whether you use water-saving techniques or tablets. How often you go out to eat. Etc.

If you don't spend so much on luxurious things and take steps to save, roughly around 150k yen for single person should be enough (excluding the apartment rentals and fare).

I think 150k would be enough with the apartment excluding fares

When I�fm in Japan I spend maybe 30k on food, including items that could be considered non essential (bottled water because tap water tastes bad to me, rice seasonings, the occasional cake). I make my own lunch, never buy from conbini, etc.

My rent is 80k. But for a single person I have a nice, large apartment 15 minutes walk from the Yamanote line. You could find a very small room in the same neighbourhood for maybe half of that.

Utilities vary, I typically allow 10-15k for the three.

Insurance and savings schemes, loan repayments, etc. vary wildly from person to person. I�fm not going to count this.

I ride a bicycle to work, if I took a train the round trip would be 388 yen. So with a budget of 150k that would leave me with 25k with which to do whatever I please. For me that would be enough, but it depends on the person.