My wife gets mad at me sometimes because I put my cigarette butts in my pockets until I can find a garbage all the time and end up smelling like cigarettes
I visited Japan like 15 years ago, your not alone over there. Everyone does that and has little boxes to store them in. This goes for all trash they make, they don't have trash cans in public since someone abused them once to bomb a train area. I loved it over there... so much care and respect for everything.
Just in case you don't know about them, consider switching to a dry herb vaporizer. The smoke is much cleaner and doesn't smell nearly as bad. Also no butts to deal with.