This song often gets stuck in my head when it's raining.... because it's about rain :P
Ame(B) by Sakanaction
I would have embedded a YouTube video but there were none to be had.

Main repeated lines are:
雨降る夜
君がくれた傘
差すと風が吹く
強く吹く
左の肩に滴る雨

(A rainy night.  When I open the umbrella you gave me, the wind blows, blows strongly.  Rain is dripping onto my left ( Read more... )

I hate the rainy season for one simple reason ( Read more... )