Originally a pachinko game series, Umi Monogatari (Sea Story) was given an anime adaptation by ZEXCS in the summer of 2009 with the subtitle Anata ga Ite Kureta Koto (That You Were There for Me). It was directed by Junichi Sato.Under the sea, two mermaid sisters by the name of Marin and Urin are enjoying their life devoting full time to floating. One day, a ring falls from the surface and into Marin's hands. She wants to find the ring's owner and return it, and takes Urin along for the ride. It's then that they run into Kanon Miyamori, a young priestess who's about to get involved in a series of events neither she nor the sisters could've planned for when Urin ends up unleashing Sedna, an evil force intent on shrouding the world in darkness. This is what prompts Marin and Kanon to become the Priestess of the Sea and Sky.Umi Monogatari is unusual among Magical Girl Warrior shows in that the focus is more on emotional development of the characters, the fights are fairly long, the girls' mentor is completely wrong about some things, most of the music is gentle piano music, and the revelation of what the Big Badreally is allows for a conclusion that's more true to life than most shows of this nature.
Tropes in Umi Monogatari include:
Absurdly Youthful Mother: Miyako, Kanon's mother. She looks young enough to be one of her daughter's friends, and has the personality to match.
Aura Vision: Kanon has an "evil aura" that everyone can see and comment on.
Balance Between Good and Evil: This turns out to be a crucial part of the series, as the islanders' unwillingness to accept and deal with the sorrow in their hearts created Sedna. In the end the darkness is accepted by them and becomes one with the light.
Bare Your Midriff: It's standard for Mermaids, but Oshima and Miyako are prone to this as well.
Bittersweet Ending: Kanon and Marin defeat Sedna, but have to separate since land and sea people are not supposed to be together. It is hinted that Kanon will keep looking for Marin.
In the DVD special it becomes clear that Kanon keeps longing to meet Marin again. She even seems to get her wish for a while, which makes things even more bitter.
Blade on a Stick: The girls are told that to seal Sedna away they must pierce her with the Spear of Light. We never get to see it.
Bonus Episode: The bonus 13th episode in which Marin and Kanon have a near-encounter after the series.
The Corruptible: Various sea creatures, but this trope is most present in Urin.
The Corruption: Sedna's influence, signified by too-bright or red eyes.
Dark Is Not Evil: Kanon's evil aura doesn't make her evil; it grants her immunity to Sedna's evil.
This is the point of the shrine maiden's song, as darkness and light must coexist.
In the end, Sedna fits this, as she was created out of accumulated sadness in people's hearts.
Darkest Hour: The end of episode 11. Marin and Urin try to fight Sedna, but have their powers drained from them. The episode closes with them sprawled on the ocean floor, near death, as Sedna's darkness flows into their bodies.
Drowning My Sorrows: Not in alcohol, but in a soothing song the island priestess sings; it even calms Marin out of her Heroic BSOD. And the ocean. The islanders' tears of sorrow and ritualistic stones falling into the sea formed Sedna out of their grief.
Earn Your Happy Ending: Marin, Kanon, and Urin have to go through a lot while fighting Sedna. In the end they don't defeat her, but accept the sorrow back into their hearts and those of the islanders, melting the darkness with light.
Incorruptible Pure Pureness: The Elder Turtle thinks Marin is this, and strives to protect her from the darkness. Instead she falls into it.
Iyashikei: This anime is about accepting your inner darkness.
Innocent Fanservice Girl: Marin's skimpy clothing is commented on when she first comes ashore, though Kanon eventually gets her and Urin to wear something a little less revealing.
Kiss of Death: Sedna's soldiers try to kiss Kanon to suck out her evil soul.
Know-Nothing Know-It-All: The turtle mentor has shades of this; not only is he wrong about which priestess will fall into darkness, he doesn't comprehend what Sedna truly is and gives wrong information as a result.
The Reveal: Kanon and Marin find out about Sedna's true nature while being almost defeated by her. Specifically, Sedna is formed from the combined sorrow that the inhabitants of the island committed to the sea.