I have been having some trouble figuring out some of the endings and have not experienced the ending plus stuff. There is one I am aware of but have not tried it yet (accept offer upon loss). Just need some hints don't need spoilers.
two not very different endings when you feed the cocoon 3 times your essence
and you don't want to beat the imp (don't now if this is a end)
oh, and what is your body height, because in the lategame, there is a nice thing with the slimes xD