While searching for a run-away cat the twins Riko and Rimu Mikogami find a strange device that transforms them into "Kirumin." It also enables them to turn into real animals. Their older sister Nagisa soon joins them. Now the three have cute, funny and sometimes dangerous adventures.

In the kingdom of Forland, a coup d'etat occurs which leads to the death of the King. In the last moments of his life, the King sends his second child, Princess Alita Forland to escape. Unfortunately, while fleeing, a life and death situation between Alita and the bloodthirsty bounty hunter Falis causes the two of them to switch bodies. Desperate for the safety of her Kingdom, Alita begs Falis to return and protect the Kingdom, offering herself as collateral. After a swift beating on the rebel forces, Falis resumes the title of Princess of Forland, leading to the birth of the most savage princess in their land, the "Murder Princess."

As the mermaid princess of the North Pacific (one of the seven mermaid kingdoms), Lucia entrusts a magical pearl to a boy who falls overboard a ship one night. Lucia must travel to the human world to reclaim her pearl and protect the mermaid kingdoms. Using the power of music Lucia is able to protect herself and the mermaid kingdoms from a growing evil force.

Lupin and Jigen planed to steal enormous money from a racetrack in New York. Their plan is perfect and the only thing remains is to wait for 6 days. To celebrate the success beforehand, they go to a town. 

Lupin parts from Jigen because he recalls another engagement. Then, Lupin saves a girl, Michelle, being chased by suspicious men. She asks Lupin to steal a diamond from her father in order to stop him from doing evil things. Lupin thinks he can get both money and a diamond 6 days later, and he accepts her request to guard her for 6 days. 

Meanwhile, Jigen meets his old fellow soldier, Ryatte, and they’re talking about another business. Then, Jigen is supposed to spends 6 days with Ryatte before the plan with Lupin. On the other hand, Fujiko and Goemon are planning to steal a diamond at a diamond exhibits. The host of the exhibition is… 

(Source: AniDB)