Leviathan -The Last Defense-

Planet of water and greenery, Aquafall. A group of meteorites that suddenly fell release evil creatures, spreading risk of extinction to all land-dwelling creatures. Leviatan, girl of the dragon clan, meets a fairy named Syrop during her daily morning magic lesson. In order to save the planet, Syrop invites Leviatan to join the Aquafall Defense, but she lacks motivation...

Syrop's sets her sights on Bahamut, the biggest princess in town and daughter of the grand mage, as the next member of the Aquafall Defense. Syrop makes every attempt to convince her to join, but instead receives luxurious treatment, and she ignores her invitation in favor of enjoying herself fully...

The guardian Yurlungur suddenly appears from out of a swamp. In order to save Yurlungur, who swallowed a foreign object now stuck deep in his throat, Leviatan and her friends enter his body to search for the object. As they wander lost, Leviatan and her friends discover something enormous...

When Syrop visits Jörmungand and her large family, she meets her three younger sisters and foster parent Travis, she learns of her love for her family. Jörmungand diligently sets out for work, but hearing a loud noise that shakes the entire village, she runs to the mine.

Leviatan is unable to forget about her older brother. Meanwhile, bringing Jörmungand with her to carry her luggage, Bahamut goes to vacation on the beach. When Leviatan learns the are heading to the beach, she goes with them to search for clues to finding her brother... Meanwhile, Syrop excitedly calls it an Aquafall Defense strengthening trip by herself!

Moments after realizing the beach at low tide resembles the location she saw in her dream, an enormous Lucasite suddenly emerges from the ocean. Leviatan and her friends happen upon the root of the threat against their planet, which releases a horde of Toripu and attacks. Leviatan and her friends transform and fight, but...

The three girls and Syrop continue walking through the desert in pursuit of the Lucasite. Leviatan attempts to magically produce water for her thirsty friends, but without her spear, the water she summons evaporates immediately. Having finally reached her limit, Bahamut stops and throws a tantrum, insisting she can't move any more.

Leviatan is wounded by the Lucasite's attack. Bahamut and Jörmungand continue to fight to protect her. However, with Toripu spawning as fast as they can defeat them, there seems to be no end in sight. Just when they think their party will be wiped out, the stone walls begin to crumble.

Coming to Rajima Volcano to heal their wounds, Leviatan and her friends decide to spend the night at an inn. While the extravagant meals, soft beds, and massages leave nothing to be desired, for some reason, the hot springs only have a little water in them. Unable to understand the reason for the loss of hot water, business has been poor, and the inn is in danger of being shut down...

Heading to the volcano to restore the hot springs, Leviatan and her friends encounter the Fire Drake. However, weakened by disease, he says he cannot even move. In order to create a medicine to cure him, Leviatan and her friends split up to gather ingredients.

Leviatan and her friends return to the ruins from Rajima Volcano. Upon entering the ruins, they discover a horde of Toripu in their path. With their will to fight burning inside them, the four girls make their way through the horde and arrive at the altar. There the Lucasite continues to attack the barrier, which seems on the verge of breaking...

Finally returning to their village, Leviatan and her friends are enveloped by a pleasant sense of weariness and relief. Syrop asks the three girls once again if they will join the Aquafall Defense. Jörmungand and Bahamut respond to her request, but Leviatan says she wishes to stay in the town and refuses...

The giant Lucasite appears in Leviatan's village again, menacing the town. Leviatan and Jörmungand are raring to go, but Bahamut has not regained her will to fight. Telling her they believe she will come, Leviatan and Jörmungand leave Bahamut to fight...