Lugh Lamfada, also called Ildhana or Lug, is the great sun god of the Celts is one of the most prominent gods in Irish mythology. A member of the Tuatha De Danann, Lugh is portrayed as a warrior, a king, a master craftsman and a savior. He is associated with skill and mastery in multiple disciplines, including the arts. He is also associated with oaths, truth and the law, and therefore with rightful kingship. Lugh is linked with the harvest festival of Lughnasadh, which bears his name. He is also known as Lugh the Long Hand, the name Long Hand coming from his long spear, Brionach.
In mythology, Lugh is the son of Cian and Ethniu (or Ethliu). He is the maternal grandson of Balor, who Lugh killed in the great war between the Tuatha D'anaan and the Fomorians. His foster-father is the sea god Manannán. He fathered Cu Chulainn with Dectera, daughter of the Ulster's chief druid, Cathbad. Cu Chulainn was also believed to be an incarnation of Lugh.
He corresponds to the pan-Celtic god Lugus, and his Welsh counterpart is Lleu Llaw Gyffes. He has also been equated with Mercury.
"A sun god of Irish lore. His name means "flashing light." He is skilled in many arts, carries his spear Areadbhar, and is known as the Long Arm. He is father to Cu Chulainn and is said to have many wives, including Bui. His grandfather Balor was also his greatest foe; during the battle of Magh Tuireadh he pierced Balor's evil eye with a magic stone."
—Devil Summoner: Soul Hackers 3DS compendium
Lugh is necessary in order to fuse Zeed into the hero Siegfried.
Lugh is one of the hidden Personas in the game that are only available through mutation which do not belong to the Minor Arcana. After hearing the rumor about Il-Dana's true form from Manannan, Il-Dana can be mutated into Lugh.
"A sun god of Irish lore. His name means "flashing light." He is skilled in many arts, carries his spear Areadbhar, and is known as the Long Arm. He is father to Cu Chulainn and is said to have many wives, including Bui. His grandfather Balor was also his greatest foe; during the battle of Magh Tuireadh he pierced Balor's evil eye with a magic stone."
—Devil Survivor 2 compendium
Lugh is the demon that acts as the key to allow the Dragon Stream to take a different form. However, due to the Void's advance, his body is damaged, and a medium will be required to channel his energy. Based on the Demon Tamers' health screening results, Io is most suitable to be Lugh's medium. However, once Lugh is unsealed, his energy scatters across the map, and the party must gather all the pieces of his energy (or recover them from thieving demons) before demons can take them away.
When Lugh's energy is sent to Io, Yamato begins the ritual for the unsealing of the Dragon Stream, where Io is synchronized with Lugh. The ritual proves to be strenuous, and the player has to regularly heal Io and defend her from interfering demons. Once the ritual completes, Io unleashes the Dragon Stream on Mizar. Depending on whether the player chose to comfort Io prior to the ritual, the strain from channeling Lugh may end up taking Io's life.
If the protagonist does not support Daichi and Io is still alive by the 7th Day, Io channels Lugh during the fight with her and Daichi, complete with her race and Racial Skill changing to match Lugh's. After the player defeats her, Lugh is unlocked as a unique demon for fusion in the Cathedral of Shadows. Lugh does not require a special combination of demons.
Like in the game, Lugh is necessary to give form to the Dragon Stream in order to defeat Mizar. Io is chosen as the vessel for Lugh by activating Lugh's seal, Brionach. Once the seal is broken, Io is possessed by Lugh as her mind is slowly overcome by the strain of Lugh's power. After Mizar is eaten by the dragon Shakko, Lugh takes full control of Io's body and shows its anger against Yamato, the descendant of the Hotsuin family who had imprisoned and treated a god like a tool. Lugh ambushes the Diet Building to kill Yamato for revenge and effortlessly defeated JP's demons that guarded the building. However, Hibiki is able to stop Lugh's attack by using Suzaku. Lugh defends itself from Baal's attack until it is defeated by both Suzaku and Byakko, leaving Hibiki and Yamato vulnerable. Realizing that Io's body won't hold on much longer, it launches its spear in the hopes of at least killing Yamato, but Hibiki pushes him out of the way and stops the spear with the Dragon Stream's magic circle. After much effort, Hibiki finally helps Io regain control of her own body, breaking Lugh to pieces. Afterwards, Lugh is available as one of Io's demons.
Io summons Lugh during the fight against Benetnasch, but is sent back when Benetnasch uses its sound waves along with the rest of the demons.
Lugh, along with Black Frost, is summoned again to fight against Nebiros who is fighting against Zaou Gongen when the path to Polaris is opened. Lugh holds Nebiros to allow Hibiki to reach the Transport Terminal until it was consumed by the Void. Afterwards, Lugh is sent to Hibiki's cell phone with other demons during the final battle with Yamato. Hibiki fused Lugh with Berserker, becoming Zouchouten.