||This paper proposes an encryption-then-compression (EtC) system-friendly data hiding method for images, where an EtC system compresses images after they are encrypted. The EtC system divides an image into non-overlapping blocks and applies the four processes, namely, block permutation, rotation/flipping of blocks, inverting brightness, and color component permutation in blocks, independently and randomly to the image to visually encrypt the image. The proposed method hides data to a plain, i.e., unencrypted image and the method can take embedded data out from the image encrypted by the system. Moreover, the method can perfectly recover the unmarked image from the marked, viz., reversible. The proposed method copes with block permutation, rotation/flipping of blocks, and inverting brightness in blocks, whereas the conventional methods for the system only copes with the former two processes. Furthermore, this conventional method requires the image-dependent information, used in data hiding, to extract embedded data, but the proposed method does not need such information. Experimental results show the effectiveness of the proposed method.