The Celaeno Library in the Pleiades star cluster is home to the largest book collection in the universe. It's said that even variants of Yiu-th only handed out at events can be found there. Mahiro is dragged along for some reason as Nyarko goes there to return a book. Hasuta, a former worker at the library, does his best to show Mahiro around, but they soon encounter two evil deities who have infiltrated the library...
Everyone forgets the flip side of youth!
¡La gente olvida el aspecto que 
tiene el otro lado de la primavera!
Todos se esquecem de sua
 juventude passageira!