There are four ways to be Stage 5 profound beast.
The First method, is through experimentation; however, those born from experimentation are pseudo-human. They live ordinary lives being monitored to see their progress. Sometimes, their actions are controlled unknowingly by a chirp.
The second, is for certain groups of profound beasts who are born as Stage 1. They advance up till they reach stage 5. This process, however, takes about 100 years. And, such beasts are killed on the spot when seen.
The third, is for stage 5 profound beasts to produce children. However, it's beyond difficult to find a mating candidate for same species.
The last method is for Stage 4 profound beasts. Once every ten years they are given a chance to evolve into a humanoid form —stage 5.
At a certain cave in the bordering forest of the two villages of Kokoro Island, such a transformation had finished.
