Demon Dragon Emperor/Chronology

Volume 9
When in Glass' world, Naofumi unlocked the Demon Dragon Shield and had part of the Demon Dragon's core crystal merged with the Dragon Emperor shard from his world and integrated into his new Barbaroi Armor. This linked the mind of the Demon Dragon to Gaelion's who was in the original shard. This allowed the Demon Dragon to sneak into the Shield.

During the battle with Kyo Ethnina, the Demon Dragon offered Naofumi the chance to use All Sacrifice Aura against him, massively increasing the stats of Naofumi, Raphtalia, and Filo for a short period of time in exchange for a powerful curse that leaves the trio crippled for a month.

Volume 12
Later, when the new Baby Gaelion ate Naofumi's Dragon Emperor shard both the minds of the Demon Dragon and the old Gaelion went into Baby Gaelion's head along with Naofumi's rage from the Shield of Wrath. This caused baby Gaelion to go out of control. The connection through Dragon Emperor fragments caused Filo's exp to be drained into baby Gaelion's body. The new entity flew to old Gaelion's mountain cave near Mirso Village in Melromarc.

After being shaken by Wyndia's words, the Demon Dragon shoved both Gaelions' minds out and took control of the beast. He made his demands clear and his intentions to use both Filo and Naofumi as sources of power in his global conquest. The Demon Dragon could lock Naofumi out of the Shield of Wrath and could upgrade it freely to make himself more powerful. He possessed the Shield of Wrath's defensive might and Dark Burning S.

After being weakened by multiple Hengen Muso attacks, Baby Gaelion was able to escape with Filo. This caused the Demon Dragon to become the Wrath Dragon. When the Wrath Dragon was defeated, the Demon Dragon's mind retreated back into the Shield, saying it will stop for now.

Volume 18
After Naofumi returned to Glass's World in order to help his fellow Holy Hero, they found themselves overcome by the reincarnator's abilities to negate their buffs and the strength of Syne's sister, so in order to turn the situation around, Therese suggested resurrecting the Demon Dragon, a master of magic, to help them. Although many were opposed to the idea, the group decided to give it a try and if they failed they would have Kizuna kill him again. In this way, the Demon Dragon was resurrected using the cores that Naofumi had in his armor by inserting them into a Dragon Egg, restricted by an ofuda (hero) in order to make to make Kizuna its master. Also, listening to Naofumi’s experience, Kizuna decided to make female the gender of the egg.

Upon resurrection as a baby, the Demon Dragon showed little surprise by the decision of the heroes of asking her help and confirmed that no ofuda could slave a Dragon Emperor, allowing her to disobey them if she wanted to but she stated that she would end dying anyway if she had to fight the Hunter Hero in her weakened state, so in order to move on she offered a truce in which she would work with them to overcome the danger of the Waves and would refrain from taking actions against humans for 100 years.

Volume 19
Information to be added later on.