The characters in this animation are from the eroge game School Mate 2 by Japanese game company Illusion. This Japanese image forum thread contains two related animations (here and here) and a colorful piece of still art also featuring these same characters. The still art appears to have once had an artist’s signature, but it has been digitally obscured. A second piece of related still art appears in this School Mate 2 forum post, which hints that a software mod was employed to create the images. Another post suggests that the amputee sex images originally came from the “guro image library” at this Japanese image board. Unfortunately, no specific artist could be identified.
Image provenance by Bacchus at Erosblog.