PhD: Phantasy Degree Series by Son Hee-Joon

Sang is a fearlessly spunky young girl in search of the Demon School Hades. Fortunately for her, she comes across a group of misfit monsters that are ditching class from the Demon school. She convinces them to sneak her into the class that normally only allows monsters to attend. Mystery, intrigue and high jinks unfold as Sang finds a way to become a monster--and begins a fantastic adventure in a devilish domain!

The monsters are the good guys as the Medusa Guild attempts to seal the doorsto all the Mahgae's.

The Madosa Guild has sealed the doors to the Mahgae of Hades! Is Sang really in league with the Guild? Looks may be deceiving, especially when a hint of her ring's true nature is revealed--the power that the ring instills upon its wearer is truly a life-changing experience. Sharpen your swords and don't cry for mommy as Sang sets off on another adventure!

The best-selling fantasy adventure continues! Chun-lang finally comes to grips with Gigantes as her adopted son...only to face losing him forever! Alcan uses his powers to sustain Gigantes--but will it all be for naught? Meanwhile, new characters emerge, including a mysterious masked woman who is looking to do a little harm to Sang...

As Sang struggles to remember her identity and purpose, Oedipus' sister Iris goes missing in the dangerous and troll-inhabited Forest of Ants! Oedipus, Sang, and their friend Hexion set off to rescue Iris--but will they find her before it is too late? And even if they save Iris, will Sang remember anything about the adventure?

Ph. D's action leads to the Master Tower--Henduh has burned down the elves' village and begins to torture Hexion, whose true identity is revealed! Can anyone stand up to the all-powerful Henduh?! Meanwhile, the other half of the group, the students from Athena, are also sent to the Master Tower by Teacher Doe, who senses that Athena's doors are about to close...

A story that features rings, different worlds, and different leagues of beings.

Sang comes full circle as she recovers from amnesia...or does she? Her past has led her to the latency mirror, where Sang must learn to accept her true nature--even though it may be a violent one!

Noel summons her protector, Halbird, to assist in attacking Order Rank. But while Noel plots revenge for her mother's death, Halbird romances Notraâ€"she is, after all, destined to be his lover. However, it seems Sang has her eyes on Notra, too. Will Noel be able to stop the Order Rank from capturing Notra?

In this thrilling volume of PhD, the good and the bad prepare for the ultimate fight--Sang gives her rings to the Order Rank before she loses her memory and transforms into Limbo again. But even with Limbo on his side, Cho-Hyun knows that they are still lacking the strength to take down the Order Rank. Will the Dark Knight Gorgant be the key to destroying the Order Rank once and for all?