New York City, 1985. Art Gile, a dancer who has been struggling with both his personal life and his auditions accidentally strikes a young boy with his car. In the hospital afterwards, the boy is uninjured but can no longer remember his past or his name. Art takes the child in and names him Jimmy.
At the same time, alien mer-people are returning to Earth for their spawning season, where they must pair up to mate, lay eggs, and die. This happens only once every several hundred years, and the rest of the time they live on other planets, but they must return to their spawning grounds on Earth in order to breed. However, there are prophecies warning that the Earth may soon become uninhabitable, and a woman known as Benjamin may be the key to preventing it, or causing it.
Then one day Jimmy suddenly wakes up in female form...
This manga provides examples of:
- Blood from the Mouth: Seth
- Creepy Twins: Seth and Teruto. Technically triplets, but the third is less identical and less creepy.
- Cute Mute: Like the Little Mermaid, Benjamin finds herself unable to speak to Art.
- Death of a Child: While it was a historical event, readers too young to remember the Armero disaster may take a punch to the gut.
- Dreaming of Things to Come: Most of the upcoming disasters are foretold in dreams, though the visions are not always completely accurate. Teruto also forces Art to see distorted visions of the future.
- Driven to Suicide: Both Art and Benjamin attempt it. Neither succeeds. Rita poisons herself and Gil.
- Gender Bender: Mermaids apparently have a child phase where they are technically neuter but appear male, becoming male or female as they reach adulthood. Like clownfish, male mermaids can also become female if needed to adjust the gender balance.
- Gender-Blender Name: Benjamin is a male name in English. No character questions this, and some comment that it's a beautiful name for a beautiful woman.
- Godiva Hair: Benjamin, frequently. Transforming into female form seems to make her male clothes disappear.
- Gorgeous Period Dress: The extras at the end of volumes often have extremely elaborate historical costumes.
- Interspecies Romance: In the past (with the fairytale Little Mermaid) one caused a great deal of trouble. The fear that one now will lead to even worse disaster is important to the plot.
- In the Blood: Most major characters are very concerned with the possibility of being forced to relive their parents mistakes. Art is the last to fall into this trope when he discovers that his father went mad and tried to murder a woman who he believed would bring about the end of the world.
- Love Makes You Crazy: Rita for Gil.
- Love Triangle: It's messy. Main contenders being Holly/Art/Jimmy, Art/Jimmy/Shonach, and Jimmy/Shonach/Seth. If you take Jimmy and Benjamin as separate the count gets worse.
- Loves My Alter Ego: Jimmy/Benjamin has some problems with this.
- Mind over Matter: Jimmy and other mermaids can move objects by telekinesis, or sometimes cause things to spontaneously shatter under stress.
- Mistaken for Gay: It's complicated, given that some characters look male when they aren't, but neither Shonach nor Art is actually gay.
- Mistaken for Pedophile: The adult male mermaid Shonach doesn't seem to understand how much he's disturbing others by appearing to be in love with a very young boy. Considering Jimmy's mentality, it may be a little disturbing even when she's in beautiful female form
- Mister Seahorse: Apparently it is possible to fertilise a mermaid's eggs even when they haven't quite become female yet.
- Mermaid Problem: Laying eggs is frequently mentioned.
- Rapunzel Hair: Common in female mermaids, and in Benjamin's case, even magically appears and disappears when she changes form.
- Someone to Remember Him By: Shonach's son though subverted in that the mother didn't live many years after that either, and the son ended up more resembling his uncle than his father.
- Sweet Tooth: Jimmy goes nuts for chocolate cake.
- Tiny Guy, Huge Girl: Rita is quite tall (6'3", tall even by US standards but unbelievably huge by Japanese) and is often drawn hunched, trying to take up less space. Gil is not a tall man, so he's much shorter and more delicate-looking than she is.
- Weirdness Censor: Art refuses to see or believe in the supernatural things happening around him.