Ai is the Guardian of Legends and it is her duty to protect them and aid them in keeping peace and order throughout the worlds. When a long imprisoned evil was released from it's chains by a mysterious figure, the Tree of Life was poisoned as a result and the universe was threathened to be thrown into conflict and chaos. 

It's incredible how a single act could affect us so much. One act made my father hated.  One act made my mother cold and bitter. One act made my youngest brother suffer. One act made me question everything I knew.

"Everybody in the world has 24 hours. It's how you spend it that matters."

Jimin really loves his Ayu.