Really interested as to why this was canceled.

I found an archived version of this series's DMM listing that has a link to the preorder for this DVD (it's the one without a cover): http://web.archive.org/web/20160822164318/http://www.dmm.com/mono/dvd/-/list/%3D/article%3Dseries/id%3D172290/

But I get a redirect error when I try to click on it: http://web.archive.org/web/20160822164318/http://www.dmm.com/en/mono/dvd/-/detail/=/cid=n_709mmrak062/

A later snapshot of the same page loads fine, but it's just an error message, indicating the page was manually deleted. DMM seems to have deleted all the DVDs featuring idols under the age of 18. Mirai Akiyoshi was under 18 at the time, but other under 18 idol DVDs were released by the same company in the aftermath of this one's cancellation, so I don't think that's why it was canceled. I seriously wonder if she was involved in some kind of scandal between her final promotional event and the scheduled release of this DVD. It would explain why Ami Sasano's career was completely unaffected.