So... is Umi Monogatari: Anata ga Ite Kureta Koto finished or not?
NO, it is not finished.
Why?
The anime finished after the manga:
Anime finished: March 26, 2010
Manga finished: January 30, 2010
... But MangaUpdates contains information about the anime adaptation and indicates that it is incomplete.
Watching Order (by release date)
Here you have all the anime relations we detected ordered by release date, so you can see the reason for this status in context and also use it as watching order.
The mangas and the non-core contents are excluded by default, but you can enable them by clicking the buttons below:
Umi Monogatari: Anata ga Ite Kureta Koto
Umi Monogatari
Anime - Base
Release date: June 25, 2009
Umi Monogatari: Anata ga Ite Kureta Koto - Shinjiau Kokoro
Umi Monogatari: Faithful Hearts
Anime - Sequel
Release date: March 26, 2010
Synopsis
Umi Monogatari follows the adventures of Marin and Urin, two sisters from the sea, who find a ring and journey to the world above to return it.
Their quest to return the ring leads them to Kanon, the ring's owner, and the accidental release of an ancient evil named Sedna.
Marin discovers she is the Priestess of the Sea, destined to seal Sedna away, and must team up with Kanon, who is revealed to be the Priestess of the Sky.
Together, these unlikely allies must overcome their initial hesitations and work together to protect both the sea and sky worlds from the impending darkness.