Kouichi Uehara is a fourth grade student living in the suburb of Tokyo. One day, he picks up a large stone which turns out to be a fossil of a baby "Kappa" who has been sleeping underground for the past 300 years, and names it "Coo." They become good friends and Coo starts living with Kouichi's family. However, Coo has a hard time adjusting to life among humans and misses his kind.

Rinne no Lagrange short specials included in the Rinne no Lagrange Season 2 Blu-rays and DVDs.

A 16-year-old boy named Shurato and his friend Gai happen to be drawn into a gigantic ball of light while competing in the final match of a martial arts tournament. When they regain their senses, they find themselves transferred to a mystic heavenly sphere with a divine atmosphere. It's soon discovered that Shurato used to be the governing king of this world and that he has only been brought to his original state. Shurato is shocked as Gai suddenly turns hostile. After this unfortunate incident, a spectacular yet fantastic drama develops involving the two.

The Sablum Empire has been attempting to take over the kingdom of Windland for many years, and are now plotting with the mercenaries Sister Hell and Darkness Knight to start a new offensive using powerful magical beings called Angels. Hyaweh, a carefree yet talented swordsman, and Priecia, who just might be the lost princess of Windland, are enrolled at the Knight's Academy in Windland to hone their skill at swords and sorcery. There they meet many friends and allies who can help them protect their homeland from the impending invasion.