Diego del Moral serves as the patriarch of the del Moral noble family and father to Juana del Moral. He perishes during an Amatsukami Imperium air raid targeting his residence, an attack occurring after the Levamme Kingdom's crown prince proposes marriage to Juana. This fatal assault directly instigates the covert mission to transport Juana safely to Levamme mainland territory.

Years prior, Diego dismissed Charles Karino's mother from her position as Juana's nursemaid, establishing a historical connection between the Karino and del Moral families. This dismissal remains an unelaborated backstory element. His narrative role is strictly limited to his status as noble patriarch and the circumstances of his demise, with no depiction extending beyond these events. Available sources offer no additional details on his character development, actions in other media, or expanded background.