User blog comment:NebulousViper/Anyone else noticing on DA?/@comment-24771943-20140605005236/@comment-24840832-20140605202951

Concept arts in general look similar because they are all trying to show the design. Front-view, Side-view and back-view, as well as one outstretched arm or different poses, close-up on the face, are all pretty common to show the expressions, head, hair and outfit in detail. What is not that similar is the drawing style, coloring style (to some extent it is similar but for iXima it seems rather notably clean to me), and the excact shape of the hair, the way the hands and feet are turned, the angles. Those are the details that really differ and this thing Orahi-Wii made shows that you can put the two concept arts on top of each other and it matches up almost perfectly. Of course there are some adjustments to fit Maya's design but you can see how her pigtails follow Miku's rather float-y ones and her hand is pretty distinctive to me (she shows her right palm in the back-view), her feet are turned inward, the way her legs are in the side-view.

tl;dr it's obvious that the artist used iXima's concept as a base and didn't credit in spite of this violating the terms and conditions of Miku's image, as Dizzyzebra said and on top of that had made it possible for her to earn money from this rather obviously traced and not credited work. The few changes made to the poses and the different design don't make it "your own".