It's pretty prominent in Azur Lane. At least one of each new wave of skins seems to have a strap conspicuously going between the breasts.
kiev_(backstreet_silver_sonata)_(azur_lane)
avrora_(not_cut_out_for_this?)_(azur_lane)
hermione_(pristine_herbalist)_(azur_lane)
charybdis_(azur_lane)
Just to list some recent skins. But sirius_(azure_horizons)_(azur_lane) and belfast_(iridescent_rosa)_(azur_lane) are some other uses.
It seems like a specific enough thing, and common enough to warrant a tag, but I wasn't sure if there was one already that I didn't know about short of a combination which isn't being used, like between_breasts + strap which I think doesn't do it justice.