Rock

I remember character A got transfered to a otome game that his sister and him played. The main couple(of the otome) became a thing, also I think it has A/B/O omegaverse, but his 2nd gender isn't out yet like it hasn't manifest to be anything yet until he meet the male lead (alpha) who's a supporting character to the main couple of the otome game.

Okay my memory is jumbled up, but here's what I remember : there are probably like 4? 3? Characters in this scene. I think character C is trying to find an antidote for someone dear to him???? Character A(female) with Character B(man) were called(?) and rumors says that this machine isn't real said character C but then it was suddenly found in seashore(?) it was said that if you place your finger inside the hole of the machine it will generate and pour a medicine but will cost your life. After the medicine fill the cup, a needle inside the machine will sting you and inflict you with poison.
I think the Female Lead can see ghosts and so she did help, they did the process and with the help of the ghost as they try to deactivate the machine to prevent themselves form being poisoned, They succeeded but in the end I think the "medicine" didn't really work after they gave it to the sick person.