How to Achieve a Perfect Ending After Entering a Messed-Up World?

Summera finds himself transmigrated into an R-18 game world where any moment could lead to a bad ending CG triggered by a nameless NPC. Assuming the role of the bullied, sickly protagonist, he is informed by a so-called deity that to return to his original world, he must successfully romance all the heroines while preserving his c*astity to achieve the game’s perfect ending.
The heroines include:
A school bully who appears and disappears unpredictably, showing blatant malice.
A seemingly gentle librarian with a peculiar fetish for marking people.
A fellow bullying victim who, after being saved once, develops an intense possessiveness.
A childhood friend who, despite daily interactions, hides a mu*derous nature.
Faced with these challenges, Summera questions, “Seriously… I have to romance all of them?”