Action Monster Big Movie

The story

Following a decline in the amount of monster movies created, Meng Qi, a director who is obsessed with the monster movie genre, becomes unsure about his persistence—he never expected that one day an actual monster would appear in front of him! In order to fulfill his dream, Meng Qi decides to cooperate with the demon girl Liya and help her shoot a demon themed movie. However, as the shooting progresses, Meng Qi discovers that things in the other world are closely related to him... (Source: Bilibili, translated)