It is common knowledge that nobles will do anything for power; lying, manipulation, and extortion are the usual tactics. However, one family is exempt from this generalization: House Grail, whose main tenets are truth and integrity. The youngest daughter, Constance Grail, is just as moral as the rest of her family, believing in always doing the right thing and helping those in need. However, these ideals do not help her when her fiancé cheats on her with another woman. Framed by his lover in the hope of her downfall, Constance has no one to hear her pleas for justice. Everyone turns a blind eye, save for one—the spirit of the infamous Scarlett Castiel—who possesses Constance and turns the tables on her accuser. However, this aid does not come without a price. Ten years ago, Scarlett was executed for the attempted murder of Princess Cecilia. But this was actually a setup; as blunt and harsh as Scarlett could be, she would never stoop so low as to use poison. She has no idea who orchestrated her incrimination, but Scarlett demands that Constance—as the only one who can see her—help her exact revenge on all those who wronged her!

Little time has passed since the Magic Knights’ final confrontation with Princess Emeraude’s Mashin. Still haunted by the princess’ death, Hikaru Shidou returns to Tokyo Tower. There, she meets her friends Umi Ryuuzaki and Fuu Hououji for the first time since their spontaneous quest to save Cephiro. Plagued by nightmares of the realm she had left behind, Hikaru is relieved to find that her companions too want to return and serve the kingdom they once so dutifully protected. The Magic Knights’ wish is answered, for at the top of Tokyo Tower, the three are blinded by the same great light they had seen on the day they first met. Once more on the back of a flying fish, the group returns to Cephiro—a world now desolate and in ruins. With the collapse of the Pillar's power, monsters freely roam the land while three nations seek to annex Cephiro with hopes of seizing the Pillar for themselves. Complicating things further is the mysterious Lady Debonair, who proclaims herself to be the rightful heir of the fallen country. Now confronting graver stakes and radically different enemies, the three Magic Knights set forth once more to save Cephiro and bring peace. With the bonds they have forged together, the trio stands united in the face of such a great challenge.

In a near future, an illness called Cagaster made ​​its appearance. It turns humans into insects. The story begins 30 years after the onset of the illness, in 2125. It follows the adventures of Kidou, a boy who fights insects. (Source: MAL News)

A series of OVA episodes released with the limited edition manga volumes. Episode 01: What You Gave Me (Anata ga Watashi ni Kureta Mono) Kokonoe, Usa, and Kagami go shopping for a present for Sensei. Eventually Kokonoe decides to make one and they all end up spending the night at her house. Along the way we learn more about Usa's love for Reiji, Kagami's love for Kokonoe, and Kokonoe's love for Sensei. Episode 02: Kuro-chan, Shiro-chan (Kuro-chan to Shiro-chan) Kuro-chan tries to become friends with Shirai-sensei. Episode 03: A Child's Summer Time (Kodomo no Natsu Jikan) The girls, Aoki and Houin go into the country to visit Aoki's family.