My Bride is a Mermaid
Based on a manga by Kimura Tahiko serialised in Gangan Wing.Nagasumi visits his grandmother near the sea during the summer.
While visiting, he goes for a swim, and drowns right after entering the water.
Fortunately for him he is saved by a young mermaid.
Later as he tells the story to his family, a young girl named San appears at his home and begs Nagasumi to marry her.Shes followed by two large thugs and they take both him and his parents to San`s home under the sea.
If that wasnt strange enough, it turns out San`s parents are mob bosses.
Nagasumi is left with the choice of either death or marrying San.
He chooses to marry a mermaid.This would likely be that, except San`s father and some members of the mob are not exactly thrilled to have Nagasumi courting San and are determined to bring an end to their relationship--or him.
And there is also the matter of keeping it a secret that San is a mermaid.