I attended back in 2002 to 2007 and they didn’t have Japanese then. I doubt they have it now but you could check what courses they have available online. If you are in the Richmond area, the University of Richmond does have a Japanese language program. Back before VCU made it to the final four, VCU was a lot cheaper than U of R. I have no idea which is cheaper these days.
VCU was part of the ISEP program and I’d guess still participates now. Their international office is probably still somewhere on Franklin street.
Since you attended (haven’t graduated?) a school in Virginia, another option is to get your GPA up to a 3.0 and then transfer to another school in Virginia (like William and Mary). If regulations haven’t changed, all schools in Virginia must accept a transfer from another Virginia school as long as that student has a 3.0 GPA. Once you get in to William and Mary, start the process for a transfer to Keio. That might take some time to pull off but admission to Keio is worth the wait.