Chasing Setsuna has proposed so far the most interesting and intricate ideas for a drama that I have seen in the community, and its concept a lot holds the potential for an awesome story in itself.
What is the plot about? Nemuri dies for unknown reasons, and because of a mistake made by Setsuna while trying to send him to the eternal realm, Nemuri ends up as a ghost and decides to escape, since he wants to continue living, but Setsuna, as told by him in his life as a priest, can't let him wander around like a lost soul.
Why so? Well, in this story ghosts end up losing everything that they had as humans in their past life, their own personality, and everything that made them themselves alive beings, and due to their desire of living, they end up possessing people and causing mischief. Nemuri himself ends up possessing a girl by accident and starts liking it, then, due to his increasing nature as a ghost, he starts to like it more and goes on a rampage looking to possess more girls as he pleases.
After possessing a girl while trying to hide his aura from Setsuna, his own obsessions as a ghost turn to Setsuna, which he decides will be the best body for him to possess. This just opens the possibilities for an amazing drama and an engaging story, the implications for Setsuna are either to take her father, already unrecognizable from what she knew, back to the spirit realm or lose her body and life in the process.
The scenario ends pretty shortly, but the idea is simply amazing, Setsuna would be trying to chase Nemuri with the help of her friend, half spirit half-human, Izuna, who has a contract attached to her, and Nemuri would try to weaken her mental state controlling people close to her so he can find a chance to take over her body. This would allow giving a lot of tension to the story.
It is overall, two people who love each other, or that at least loved each other before, Father and Daughter, try to win a chase one over the other. In this case, we are sharing the perspective of the antagonist, which allows the audience to see some fetish focused action like MtF possession and where Nemuri gets the advantage of the bodies of who possesses, there is also some mind control since all the thoughts he has and actions he does while possessing others are felt like their own by the possessed when he gets out.
While it sounds like Setsuna doesn't stand a chance due to her lack of experience as a priestess, her friend, Izuna, is shown as a powerful being who carries a sword that can kill any ghosts and aberrations without any difficulty, and overall her character is given a mysterious aura; as I have said before, she is a half spirit half-human who was taken care of by Nemuri as a kid and now, respects him a lot, because of that, she is ready to keep Setsuna away to help Nemuri live his new life, nevertheless, due to her contract, if she is ordered by Setsuna, she has to take care of Nemuri; that just adds another layer to the whole picture of things, touching topics like loyalty, friendship, and some High Fantasy since Izuna is part of the spirit world.
Some people would say that this version of Nemuri takes too many liberties by making him the same as a horny teenager, but I think this depiction is quite fair with his nature as a lost soul. Nemuri going from a respected priest to lustful ghost plants a lot of questions and implications for this character, a complete mind degradation so to say. In the end, he could become an evil being with his plan of taking over Setsuna and become the new priestess of Izuna. Izuna as a half-spirit character that has to take both sides between the father and the daughter is interesting as well because that morally ambiguous, completely loyal, and skilled character interpretation, fits her a lot.
Sadly, this scenario was put on hiatus in very early stages, and even when it hasn't been totally canceled the last update was done 3 years ago, and this time it hurts a lot because the story and the plot it's just so good. It has several leads and has a big fetishistic appeal, yes, it's true, a lot of the possessions are used just to make you feel horny, but the story in itself can offer a lot for those who want some great drama, if you do not take it that seriously and let the scenes that are only for sexual appeal be themselves, you will enjoy this scenario, it really seems that it can offer the best of worlds, but the rest of the story is yet to be seen.
Overall, in the state it is now, I can recommend it if you want some MtF Possession action (sexually-focused) as well a bit of mind control, but I can also recommend it if you want to check out more about the whole concept by itself, which is sincerely awesome, even when not a fully-fledged story. (it ends just as it starts and plants the plot) it's a good concept for a compelling story.