That was my favorite summon in the game. :x3:
Oh you know I think I am thinking about The One King from Suikoden Tierkreis. Every person who defeated him became The One King themselves and proceeded to destroy until someone could destroy it.
Same concept though. The fruit may have driven Kaguya into becoming wild with power and eventually that corrupted her and her body to the point she became the Juubi. Then as a means to protect the world the two sons painstakingly fought against her and sealed the halves within themselves. Legit?
^^^ This is what I have been thinking, how else would an immortal goddess with unlimited power just die, this seems to me the only logical way she could have died.
She transformed into the Juubi and was then sealed by her sons.
The sage sealed the chakra inside him, whilst the brother sealed the body of Kaguya, thus creating the reaper death seal.