What is its native resolution? I'll look closer when I get to work, but it sure seems to me that you are dealing with an older 4:3 SD anime. I see no need to really filter and I'd suggest you beware of over filtering.
Besides a resolution change to 640x480, it might benefit from some noise reduction or temporal smoothing. Heavy stress on the might. I see what does seem to be some fairly annoying noise, but you don't want to eliminate grain or texture at the same time. I'd say be conservative with any filters you choose to apply.