>>2548540They're simply the tankoubon volumes in an ebook format.
Tons of places including
Amazon.co.jp and
honto.jp sell those, but I'm not sure where you should and even can buy since I haven't had any reason to get into it. The Daily Japanese thread or maybe the buyfag thread on /a/ probably have more people who've tried them out.
Besides the opening color pages that are also in the normal physical tankoubon, there are no extra color pages from what I've seen.
I suppose everyone already figured it out, but Asagichou has translated the newest chapter. No one has said anything about it though, so here:
https://asagichou.wordpress.com/ 