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...