Twelve Months is the story of an orphaned girl named Anya. When a spoiled princess, who is also orphaned, sees a picture of a Galanthus, she immediately wants one. However, the Galanthus only blooms in spring, in the month of April. It is New Year's Eve and there was no way that such a flower can be found in the middle of the winter. The princess offers a basket of gold to anyone who can bring her a bag of Galanthus.

Lucifer has been awoken from his eternal slumber by the spirits of Eris, Abel and Poseidon. He has come to kill Athena and fulfill his heart's burning desire: becoming the strongest of all the gods.

Satoshi and his friends get lost in an unknown wasteland. They eventually come across a "Water Pokemon Show" performed by the star of the Mariner Troupe, Hiromi. Hiromi is a descendant of the troupe of Water People able to communicate with water pokemon, and she tells our heroes the legend that's been passed down by her people for generations. According to legend, a temple the Water People built called "The Water Temple Akuusha" rests somewhere in the ocean, and a treasure called "The Water Crown" is hidden there. It's said that no one has ever seen this treasure, but that changes when a Pokemon Ranger named Jack Walker (aka Jackie) appears to chase aftert it.

Jackie is on a top secret mission that has him protecting the egg of the leader of the water pokemon, Manaphy. This pokemon, called the "Prince of the Sea," needs to be taken to the Water Temple Akuusha, so Satoshi-tachi and Hiromi decide to help him. Along the way, a pirate named Phantom attacks our heroes from his great submarine. Phantom plans to use the Water Crown's power to help him conquer the world, but he'll have to solve the mystery of Manaphy's egg first. When the Rocket-Dan get into the mix, Jackie uses his Capture Styler to borrow the power of a nearby pokemon to stand up to them. Satoshi and Pikachu enter the fray, but they still have to contend with the attacks of Phantom's powerful high tech mecha! Suddenly, the egg starts to shine with a vivid light, and Manpahy is born! 

What is the mystery of the legendary treasure? What mysterious powers does Manaphy have? Can Satoshi-tachi and Jackie complete their top secret mission? The journey to reach the Water Temple Akuusha has begun!

The story follows Benio "Haikara-san" Hanamura, who lost her mother when she was very young and has been raised by her father, a high-ranking official in the Japanese army. As a result, she has grown into a tomboy. Contrary to traditional Japanese notions of femininity, she studies kendo, drinks sake, dresses in often outlandish-looking Western fashions instead of the traditional kimono, and is not as interested in housework as she is in literature. She also rejects the idea of arranged marriages and believes in a woman's right to a career and to marry for love. (Source: ANN)