Uniform SurviGirl I (2008)

17 year old schoolgirl Sakura visits a Samurai theme park called Survival Land with her friends where they're supposed to go up against some cosplayers dressed as samurai but things go horribly wrong when one of the cosplayers gets infected after finding a strange flower in the theme park's grounds and cutting it with his sword. Some black liquid sprays him in the face and the next thing we know he's infecting the rest of his colleagues as they turn into zombies. Soon the game turns deadly as the undead cosplayers start attacking the girls with real weapons. They need to find a way to escape from the place.