I Have a Demon Prison

When Li Tianxing traveled to another world, he got a growable demon-suppressing prison in his dream. By suppressing the demons, he could obtain feedback on his cultivation and continuously enhance his cultivation strength. He could also suppress the demons, allowing the demon-suppressing prison to grow and evolve. From then on, Li Tianxing transformed into a righteous monk who hated evil and was praised by everyone. The cruel and cunning green-headed devil? A blood demon with red hair and red eyes and endless evil aura? An invulnerable iron demon? Hum, I, Li Tianxing, suppress them all! No matter how many demons come, I won't be afraid. Let them all be transformed into my cultivation! Li Tianxing transformed into a demon-suppressing master and traveled around the world, suppressing countless demons. Until one day, he discovered that the demon cultivator seemed to be a demon too? Well, it looks like there's one more business. One day, Li Tianxing was even more surprised to discover that the inner demons generated during the tribulation... Were actually demons! Haha, haha, Li Tianxing smiled slightly in his heart. From then on, when he walked around the world, he had an extra sign in his hand - the inner demon killer, never miss!