Phos approaches Diamond for advice on what to add to the encyclopedia when another group of Lunarians appear. Diamond's sword is knocked away while trying to deflect the Lunarians' attack, but they are saved by another diamond-class Lustrous, Bort, who Diamond laments they can not surpass. As Bort scolds Diamond for putting themselves at risk, another Lunarian heads towards the school while Kongö is deep in meditation. Diamond follows Bort as they fight the Lunarians, and Phos is swallowed by a large snail creature, whose acidic form starts to melt away Phos's body.