Resembling a giant cannon, the Lacuer Hope is named for its developers from the Kingdom of Lacuer and the faith that Lacuer's inhabitants place in its abilities to protect them from outside sieges. The weapon is created by the family of Leon D.S. Gehste, who are all accomplished scientists.
When monsters from the Ell Continent begin to attack the Lacuer Continent, Claude and his friends take refuge in Lacuer, where they happen upon Leon's family in the castle basement. They are discussing the finishing touches to put on the Lacuer Hope, and they need an Energy Stone from the Hoffman Ruins to do this. Leon's parents hastily encourage Claude's party to escort Leon to the island where the Ruins lie and help him retrieve the mineral from its depths. Given Leon's conceited nature, he is disgruntled by this, but nevertheless accepts the offer.
When the party returns from the Ruins with Energy Stone in hand, Leon immediately rushes to the Lacuer test facility and completes the weapon, which is transported to the Lacuer Front Line Base. The stalemate that existed before the weapon arrived is blasted away with a beam from the Lacuer Hope, which obliterates a large portion of the Elurian monsters.
The King of Lacuer encourages Leon's family and Claude to bring the Lacuer Hope across the ocean and stage a suprise attack on the Elurian colony core. While on the journey, the winged demon Cynne appears overhead and dives towards the party ship. Leon smugly initiates another energy beam from the Lacuer Hope, but Cynne conjures a powerful magical shield that nulls the attack. Leon is left speechless, and Cynne promptly dispatches Claude's party and sends them into the sea. Leon's family similarly abandons ship in fear, and Cynne takes control of the boat and the Lacuer Hope, intending to use the weapon for his side's advantage. However, the monster is defeated at Eluria Tower by a returning Claude and his friends, and the energy cannon does not see a day of destruction again.