Manga: Araragi Tokkyuu 522i22

I'm having trouble confirming that 8 volumes were published in country of origin. No matter where I look, I can only confirm 3 volumes. Can anyone out there confirm 8 volumes? And then the scan of the cover image of the 8th volume?

There are only 3 volumes. I have no idea why someone would mark it as 8. There's enough proof in the fan-made covers from the releases of Manga-Daisuki. The first volume had 238 pages, which is much more than 100.