Okay, the reason he was hard to assemble was because his joints were sized a little too tightly, so had to twist the limbs onto the ball joints as shown in a video. Doing so, however, made his right leg and left arm ball joints loose. He's/it's the tallest figure out of them all so far.
So, it would seem the package these four books came in was much too large, and it had appeared the books were set on their openings inside the box, because when I opened it the books were messily shifted inside the box, leading to this book getting a nice bend in it:
It would have been better if the books were on their back covers, like they're supposed to be, and in a much more appropriately sized box, but nonetheless I'm happy with my books.