You mentioned not wanting to invest a lot of money, and that's fine, but having additional capital may still be required.  

I found out that their all products are energy star and BBB rated windows and Doors.

They were pretty reasonable compared to Post Card Mania which is an awesome company but found the same product for cheaper and locally.

People love to rent something for a week or two up north during the summer.Best wishes for profitable real estate and a productive school year!

Being that you are in Japan that ads additional difficulties.  

Free cash of $1,300/month (the $1,150 you are currently paying in mortgage and utilities plus $150 cash) could then be used to pay towards principal on SL and car not, accelerating debt pay down.78% RR on 20k minus 5% avg SL and Car interest and 4% mortgage interest = IRR of 69%I think (assuming I'm looking at this the right way), using your 20K in cash soldiers to generate additional income is more advantageous than using it to pay down debt.

In addition, I'd own the liability of paying for stuff when it breaks, and my insurance would cost more.

Additional keywords: Indy, Indiana, Indianapolis

Additionally, I've been told ( and read on many sites) that if a junior lien holder is foreclosing... the senior lien is Not wiped out and the new owner becomes responsible for The entire amount owed on the home.  

If you have any additional questions and or concerns PM and I will be more than welcome to help.