The Director and founder of the Bantorra Library. His ability "Tearless Ending" enables him to make snow fall on a global scale and anyone who touches it will fall into an eternal deep sleep. This is due to the fact that in actuality he, like Zatoh Rondohoon and Enrique Bishilie, is a book eater and because of his nonentity entrails, can have many magic rights. However his power level is incomparably higher than either Zatoh or Enrique as he had consumed at least 100,000 books.
In the past, Ruruta was humanity's savior in the face of Orntorra's promised destruction. For that reason he became strong and eventually defeated the Beasts of the Final Chapter.
However, Niiniu, a girl for whose sake he fought, was the core controlling the beasts. It turned out that in an attempt to thwart their romance, Ruruta's retainers made him forget her by drinking from Argax. These same retainers beat Niiniu, crushing her throat and nearly killing her after claiming that Ruruta had abandoned her.
As she lay buried and dying, Orntorra appeared and explained that this world, world number 645, now faces destruction. Because humans repeatedly commit the same mistakes, a new paradise (646th) must be created. Niiniu accepts destruction and gains control of the beasts who quickly dispatch the treacherous retainers. She then transforms into a stone statue.
Ruruta eventually remembers Niiniu after Lascall Othello extracts her book for him to read. He becomes desperate at what he has done. Upon his return, he destroys his imperial capital and his followers and establishes Bantorra and the Church of Drowning in God's Grace in order to bring Niiniu, whose book he consumed, ultimate happiness.
If he can't succeed in bringing Niiniu the ultimate happiness, he feels he must fulfill her final wish of destroying the world which he promptly sets out to do after finally emerging from his tree.