Youkai Mountain is a fictional location in the Touhou Project series, a popular franchise of Japanese bullet hell games. It is depicted as a mystical mountain inhabited by various youkai, which are supernatural creatures from Japanese folklore. The mountain serves as a home for these beings, who often interact with humans in unique and sometimes mischievous ways. The mountain is characterized by its lush forests, steep cliffs, and hidden paths. It is also known for its diverse ecosystem, featuring both flora and fauna that are often influenced by the presence of youkai. Visitors to Youkai Mountain may encounter various challenges and adventures, making it a central setting in the series' stories.