> I will do only characters I like.

What about depicting a rather unconventional concept, with not much care for what characters get used?

Basically take two rather different-looking characters (e.g. Rin Tohsaka and Luvia Edelfelt), have them decapitated and/or debreasted in some manner whether intentional or accidental, and then afterwards their parts are either put on display or in a casket or whatever, but the parts get mixed up for whatever reason and each girl's torso and/or breasts get mistakenly "allocated" as having originated from the the opposite girl.

So using my example characters of Rin Tohsaka and Luvia Edelfelt, the idea is that the end result would be Rin's head ends up being paired with Luvia's torso and/or breasts, and Luvia's head paired with Rin's torso and/or breasts.

Attached is a random unrelated fan image of Rin and Luvia demonstrating what I mean by "two rather different-looking characters"