The biological divergence between the two brothers.
Hagoromo and Hamura discover the dark truth behind the "Divine Tree Ritual." They learn that the villagers sent to the tree are not being blessed, but are instead being drained of their life force to produce a fruit.
Mixed (incorporates anime-original backstory for Kaguya)
The brothers encounter the Great Toad Sage, Gamamaru , who reveals the truth about their mother’s origins and her arrival from the stars.