Marin and her younger sister Urin are seafolk who happen upon something quite strange: a beautiful silver ring lost beneath the waves. The kind-hearted Marin, intent on returning it to its owner, drags a reluctant Urin along with her to the sky world despite reminders of a turtle elder who left for the surface and never returned. After locating the ring's owner, Kanon Miyamori, they learn that Kanon had tossed it into the sea after her boyfriend dumped her earlier that day. Though Marin insists that such a lovely item should not be thrown away, Kanon discards it once again. As they search for the ring, Urin becomes separated from the other two and accidently breaks the seal on a stone coffin, releasing an evil being known as Sedna. Sensing Sedna's release, the formerly missing turtle elder, Matsumoto, reveals himself to Kanon and her companions, naming Marin as the Priestess of the Sea. Together with the Priestess of the Sky, she has the power to seal Sedna away again. And as luck would have it, during an encounter with one of Sedna's minions, Kanon discovers that she is the Priestess of the Sky. Though Kanon is hesitant, she and Marin decide to work together to save the world from the evil that threatens it.

In a future governed through the lens of a camera, where people eat synthetic food and pursue an online existence in lieu of physical contact, a group of children begin meeting up in the real world. The aloof Ayumi Kono, the genius hacker Mio Tsuzuki, and the socially awkward Hazuki Makino set out to find the fourth member of their group, Yuko Yabe, who has gone missing. With the help of Myao Rei, an unregistered citizen proficient in martial arts, they are able to find Yuko. However, when their situation takes a sudden turn for the worse, the group stumbles headlong into a dark mystery that challenges everything they know about their world.

Orphen and his gang has set out on an all new adventure with many monsters to battle and no peace and quiet. But a new friend has joined the group. Her name Lycorus who was sent to find Orphen. Many mysterious shadows are overhanging over head. (Source: ANN)

Following her graduation from middle school, Konomi Yuzuhara enters the same high school as Takaaki Kono, her childhood friend. As the new school year begins, they meet their childhood friend Tamaki Kosaka, as well as many new accquaintances. Unbeknownst to the group, their encounters with each other will soon lead to many memorable adventures. (Source: ANN)