My grandfather passed away 5 years ago and he gave to me his watch before he leaves.
It's very special to me,because he was wearing this watch everyday. My grandfather told to me he bought this back in 70's in Japan.
I couldn't took a pic of the back(sorry for poor photography skill ! ) but it says,
CITIZEN WATCH RESISTANT
XXXXXX( SIX OWEN NUMBERS)
GN-4-S JAPAN => 9
and this watch is not using any battery. this watch gets the energy from the light which is solar power.