Wise Turtle Publishing

Is it okay to upload the OVA iconic character on my Facebook account or does that violate some sort of Terms of Use?

Of course! After all, at worst, no one knows what it's from anyway. At best, it's free advertising.

Good to know. You never know what sort of legal hoopla you might step into nowadays, regardless of intention, so I thought I should ask first.

True. If we were to go over the actual legalities of it, it would've been "illegal" up to the point where you asked me. Once I had given you permission to use the art for the stated purpose, you were in the clear. Of course, I'm not sure how legally sound a forum post is, but I do appreciate you taking the time to ask me, just the same.