I'm not sure if it's a oneshot or the first chapter of a series or if it's a bonus chapter.

The story is:
The heroine meets woman A and both of them gathers with others from a suicide group. As they are driving to the suicide location, they are drugged. When they wakes up, the woman A is gone and they are already inside a bunny costume. Turns out they are part of woman A's hunt game. Woman A explains that if they can successfully escape from the mountain, they will be free and receive a prize. The mountain is filled with a trap and a man falls first. As the heroine tries to escape, she fell into a corpse dump and got a weapon. Heroine fights woman A and escapes. She meets a bunch of campers and just as they are phoning for help, woman A appears and slaughter them all. Heroine escapes again. Just as she about to cross the mountain, woman A slices through her legs. The heroine fell and into a pavement road. Woman A frustratedly acknowledges her win and throws her her prize, a bunny tag.

The artwork is not too good but it's very gory. I hope someone could remind me of this manga.

Thank you in advance.