Motokage? Isn't this Tokyo? The first two images on the pixiv account are on tokyo's site. Though it's a little strange that there aren't more pictures on there.
If it's not him, then it's someone who stole his pictures / perfectly replicates his art style.
Actually, I'm not sure if Great Akuta is a circle with more than one artist, it sure doesn't seem like it, but it makes me wonder why this pixiv account isn't linked to his mainsite, considering his style is so telling.