In the tutorial you are given two artificially low leveled demons. Why is neither of them Cerberus?
Who knows? Tam Lin and Alraune were pretty cool though.
There is a big deal that stoping the marriage ritual will hurt the villages livelyhood. Why does no one care said livelihood is based on assassination. Seriously, what!
Why does everyone accept the story that the Tento were driven away for their looks and never suggest it had something to do with the fact that they warp human women to reproduce
Because the Japanese are very xenophobic. Being different is all they need to persecute them. What they do to women was probably found out later and only fueled their xenophobia even more.
Shiva isn't fused via Rangda and Barong. Why? Even Devil Survivor had it, and that was pretty much the games only "unique" fusion.
Another note on the Fukoshi... Why are they unable to breed the insects required for assassinating on their own? The Tento blessing is eventually found out to be the gift of said insects in exchange for Tsukigata daughters, so while this is incredibly heartless, can't the Fukoshi just let them die off with age after the deal's been done? And if they don't die, why are they so concerned with having the daughters to populate? If ever Lord Tento gets mad the town should also have no problem against it, given their livelihood. It just doesn't make sense for them to be so fearful.
What happened to Kaya? Her house is still there, many minor characters from the first game are still there... but she's mysteriously missing, and so is her entire family.