Mirumo is the selfish and chocolate-loving prince of a magical kingdom. As the successor of the kingdom, his father wants him to travel to the human world and study -- but Mirumo has other plans! Due to his unwillingness to go, the King declares that Mirumo must be married at once to his betrothed, the beautiful and clingy Ririmu. Things get even worse for Mirumo when Minami Kaede, a shy girl with a crush on the handsome Yuuki, wishes upon a magical cup for a fairy to give her the love she desires -- thus pulling Mirumo into the world of humans! But Mirumo and Kaede are not alone; Ririmu soon follows to help Yuuki, and Yashichi the Ninja to help Minami's rival for Yuuki's love, Hidaka Azumi! Hilarious antics abound in the new and complicated lives of these friends and enemies!
One clear festive evening, Lucia, a mermaid princess, rescues a young boy from drowning. With him, she leaves the source of her beautiful singing voice: a pink pearl necklace. Several years later, Lucia has grown into a young woman, and embarks on a quest to the human world to reclaim her pearl and find her lost love.
Mermaid Melody and Selfish Fairy are remarkably similar; both have various cute creatures/monsters and villains who are just as cute, and both have a female protagonist who is trying in vain to find a boy she loves. Beyond that, they just feel identical (and are aimed at younger folks). Mermaid Melody is a little more of a magical girl/transformation anime, while Selfish Fairy is a bit more random and slapstick. Nevertheless, if you liked one, you'd surely like the other.