-edited several times due to posting fails
Well since the op seems to have extensive knowledge Japanese Myths (where did you find all that great information?
) I would like to suggest Yuki-ona like creatures
The Yuki-ona or Snow woman was basically sort of like snow succubi(sometimes vampiric and sometime just killing travelers for sh*ts and giggles) She even devise tactics like pretending to abuse a child killing any good Samaritans.
There is one story in particular about a young handsome boy who was caught by a Yuki-ona the Yuki ona let him live, simply because she thought he was attractive(potential pedo-bear like monsters perhaps?) on the condition he never tells anyone about the encounter, if he did tell she would kill him. When the boy grows up, he tells his wife about the Yuuki-ona.
The wife said,” That was me, I was the Yuki-ona, but I told you not to tell ANYONE about that day or I would kill you, but you are the father of my children so I won't kill you, but if you EVER lay a hand on my babies there will be hell to pay!".
Luckily, the man was a wonderful father
So along with pedo bear like creatures we could have mercy based on certain aspects of an individual (In this story beauty and later on child rearing) and potentially creatures (night hags or those (fox spirits I forgot the actual name) morph into human forms and potentially integrate into human society for various reasons, in some cases even integrating just to make sure someone follows through on a promise and maybe even showing gestures of forgiveness. Maybe even cases (if toady ever implements a “life” mode involving child-hood) when a child not-knowing any better sets a monster or a beast free from a trap of some sort, the monster could act as a guardian or potential suitor or love interest in the future (or with curses and powers in the next update infects the child and instructs them to come to a certain location when they feel they are ready.
Speaking of such scenarios maybe we could have catastrophic events brought upon people by benevolent spirits that had good intentions but whose actions result in serious consequences. (A dwarven king Midas but with cotton candy perhaps?)
Maybe a recreation of the Yuuki-ona’s story but with the man being a dead beat father