Just to let everyone know, the roof repair guys came to my place and
they found the problem. The problem wasn't what the inspector expected.
It was because there was about 1 inch diameter hole on the roof. The
repair guys said that a pretty big branch probably hit the roof and
made the hole.
Again, as i said before, I decided to pay for the repair and stop
asking around who's fault it is. Fortunately, it didn't turn out to be
a huge problem so we didn't have to pay too much.

For those people who thought I wasn't reasonable, I guess I wasn't.. a
little.
but think about it.. you paid more than 700K for the house, and your
roof is leaking as soon as the rain starts and the master bedroom is
wet... who can easily be reasonable. It just feels like my mind started
to leak right after finding the leaking roof.
I assume everyone understands the human being's nature, Imperfection.

Anyways, we got the roof repaired and there is no more leaking. Problem
solved!!
Lastly, thanks to everyone who shared my chaotic problem from the
beginning.