It's been six years since that summer adventure when Taichi Yagami and the rest of the DigiDestined crossed over to the Digital World. And nearly three years have passed since the final battle between Hikari Yagami's group and BelialVamdemon. As the peaceful days passed by, at some point the gate to the Digital World closed. Not even the DigiDestined know what caused this, and time alone continues to pass.

Marin is so filled with doubt and grief, that she can no longer become the Priestess of the Sea. Her only hope is Kanon, the girl who has always carried darkness in her heart, yet still found a way to become the Priestess of the Sky. What is her secret?

Marin and Urin used to be inseparable. Where one would go, the other would always follow. But now, Urin is walled off and locked away, beyond Marin's reach. Is this what Urin really wants? Will they ever see each other again?

Urin has returned to the sea, but something's not right. Ever since the eclipse, Urin has been cold and distant... Marin rushes back to the sea as well, but Kanon can't follow. She needs to find a way to breathe underwater – she needs the Ortelius Ring!

Everything is falling apart. Urin is missing... The sky is black... Marin can't shake the cold grip on her heart... Ghostly purple butterflies are swarming over the sea... And the eclipse, that blood-red ring in the sky, continues on without end.

A solar eclipse is coming, but while it should be a happy event, Matsumoto has a dire warning. If Kanon finds her heart drawn to darkness during the eclipse, she might lose her ability to become a Priestess. Marin vows to protect her, no matter what!

Kanon needs to be 100 percent pure, but right now, she's way too evil. So, to help her in her quest for purity, Matsumoto gives her a treasure map. If she can find the mysterious treasure hidden on Kagero Island, it will grant her the pure heart she seeks

Since Marin has a newfound duty as Priestess of the Sea, she'll need a place to stay. What better place than Kanon's house? Kanon thinks it's the worst idea she's ever heard; but as for Marin, this is the perfect chance to learn more about her new friend.

Something dark and sinister was released from that stone coffin. Rain is pouring down, the seas are churning, and... a turtle statue just came to life?! His name is Matsumoto, and he knows the truth behind what's happening.

A year has passed, and Kanon returns to spend the summer on Amamiko Island. Although Kanon's life has completely changed, things on Amamiko seem to be the same as they always were. Kanon can't help but wonder... are things the same for Marin, too?

The truth behind Sedna's identity has been revealed, but it's too late. The Bermuda Stones are shattered, and Urin has been completely changed, taking on Sedna's physical form. In the suffocating darkness, is there any hope left for the light?

Things are only getting worse... Not only are the people on land under Sedna's control, but so are the people of the sea – including Warin and Sam! They climb out onto the shore, armed with weapons and ready to fight. A terrible battle is about to begin!

As Sedna's power grows, a haze spreads out from the sea and covers the town. Even though Marin and Kanon have gotten stronger, they're no match for the darkness seeping its way into everyone's hearts. Kojima, Suzuki, Miyako... no one is safe.

Marin and Urin are sea folk, people who live in the ocean. One day, a ring falls from the "sky" - that strange place above the water - and the two girls decide to find its owner. But while the surface holds many wonders, it also hides a great darkness...

In the aftermath of Symbols break-in, the Gowas scramble to try and prevent their flight from the country. Yushiro, still reeling from the frightening truth of his existence, goes to the Stage of Stone in Kinashi for answers.

The Gowa Corporation begins analysis of the enemy TA's artificial muscle salvaged from the skirmish in Belgistan. Meanwhile, Symbol plots to break into Gowa's research facility and recover information on Yushiro.

The 3rd Experimentation Company is returning to Japan along with Yushiro, but others are not so sure about letting them return so easily... America wants to get their hands on the TA technology.