The Morning Star Aldan「明星 アルダン Myōjō Arudan」 is a Sacred Treasure belonging to the Boar's Sin of Gluttony, Merlin.
Aldan is a small crystal orb that appears in Merlin's hand when summoned floating around her palm.
Much of the abilities of Aldan has yet to be seen but so far, it was seen being used in conjunction of Merlin's telekinesis and can display locations whenever Merlin wishes to look into it. It is also used to channel most of Merlin's spells like Exterminate Ray. Merlin can even transfer her soul into Aldan to circumvent some status ailments, and possibly much more grievous physical damage.
- Aldan is the fifth Sacred Treasure to be revealed in the series.
- Aldan is named after Merlin's mother in Welsh mythology, while the title, "Morning Star" refer to the Devil's true name, Lucifer, who people believed is Merlin's father.
- Aldan shares several abilities with the Bauble of Princess Eilonwy from the Chronicles of Prydain, being a magic orb able to float under the command of its owner; the main difference being Eilonwy's bauble was only able to produce light while Aldan is more of a spellcasting aide.