Sein, the Globetrotting Penitant, the Wandering Pilgrim, the Redeemed One, and the Seventh Spirit Tree of Nibel.

Sein was just about the least likely spirit to succeed Neriah, the sixth Spirit Tree of Nibel. She was born from Light mixing and was not a formal child of Neriah, her family had only relatively immigrated to the Forest, and she was born with terminal heart-Light Decay poisoning, a fatal condition that caused her very body to generate and poison itself with Decay over time requiring her to take Light injections to slow down the corruption. A condition that also normally make it impossible for a spirit to ascend on death.

Odds were not in her favor to say the least. Despite this, Sein was born a Called and embarked on a series of wild adventures all through the world.

It seems that trouble always follow Sein wherever she goes ; even after ascending as a Spirit Tree, there was this little incident involving a giant angry owl, a gumon Decay cultist, and an army of Decay monsters who have kept a grudge against her for what she did as a spirit. Sometimes, her wacky hijinxs are comical and funny. Sometimes, the random crap that happen to her is... less comical.

Sein may have been a priestess of the Light and was fully dedicated to her job, with her faith strong... but she also happened to be significantly akin to a hotblooded anime protagonist in many ways. Some say that maybe she would run into less surreal antics if she actually thought things out before leaping into action. Also, prone to denying that she's totally checking out (and want to "know better") males around her. It fools nobody ; she definitely didn't wait until she became a Spirit Tree to start producing heirs.

Some people might recognize Sein as the biological mother of a certain spirit known as Ori. That would be correct. Since she cannot punch people in the face anymore, mentioning the Great Storm to her may instead result in her grabbing a heavy boulder with her Light powers and then making it "fly" and "mysteriously land" on your head.