all i can get from this is guy gets turned into girl, with a girl getting turned into the guy two girls do a sexy time, then girl who turned guy to girl kills(?) girl turned guy with drug, then something else at end
@Levenstein The plot twist is actually a little more complex than that. One thing that you have wrong is that Tooru (the guy) wasn't swapped, but rather copied over into Rio's body.
Sae (the doctor) is a psychopath who believed she was in a love triangle. Sae was in love with Rio (the senpai). Rio said that she loved Tooru, while constantly bullying Sae. And Tooru was constantly hitting on Sae, culminating in the confession we see near the beginning. Through overwriting Rio's personality with Tooru's, Sae hoped to create her ideal world where Rio loves her and there's no annoying man pestering her. However the big reveals are that:
A) Rio loved Tooru the whole time but was too afraid to confess.
B) Tooru's copied over personality is fading and Rio's is returning. But Rio/Tooru doesn't care anymore. They're happy.
1) Tooru (dude) comes from a rich family but is otherwise a useless playboy who got his job through connections and is constantly hitting on Sae (blond girl)
2) Rio (black-haired girl) loves Sae but is too tsundere to admit it and so she bullies Sae while saying she loves Tooru in order to get between them.
3) Sae is some genius brain scientist who loves Rio for some reason despite the bullying
4) Sea "accepts" Tooru's confession but tells him that she only loves women, convincing him that she can transfer his consciousness into Rio's body for yuri love-making. He sets his affairs in order so no one will look for him after disappearing.
5) Sae reveals that rather than transferring his consciousness she just copied it into Rio's body so that she could make love to a "Rio" that loved her back rather than bullying her, showing Tooru their sex videos before killing him, knowing no one will look for him.
6) Rio's consciousness, which was overriden by Tooru's, slowly resurfaces. "Happy" yuri end.