This anime has popped in to my head semi frequently over the past decade and I have no idea what it is called. Pre-Isekai is set in a future Japan. I remember it was kind of grungy art pre isekai and one scene that sticks in my head is that two characters are wearing gas masks and discussing how bad the air pollution in Tokyo has gotten.
The main character is older and a delinquent type. The sword he has has grooves in the handle he can put gems in that power it up. I think the gems looked more like stones? That is all I can remember. I know for certain it is not Rave Master.
Thank you for any help!
