Birthdays and Ages of the Princesses.
Okay. I've gotten some information from Pearl Song. I credit her to all the information on the fortune telling and birthday pages.
In the August 2004 issue of Nakayoshi used a frontpiece of Mermaid Melody. The illustration listed the birthdates of all the Mermaid Princesses [excluding Siera]. Each birthday also included the date and day of the week the princess was born on. Years were NOT included. [These dates are again found in the back of volume 5 in the manga]
Lucia Nanami: Born Monday July 3, 1989. Lucia is 13 years old in the beginning of the series, and later she turns 14 [Episode with the beach fire]
Hanon Houshou: Born Wednesday, May 24, 1989. Hanon celebrated her 13th birthday before the start of the series. In the manga, there is a flashback of this in chapter 2. However, nothing is noted in the anime.
Rina Touin: Born Saturaday, September 2, 1989 [Hard to believe Rina is the youngest in the trio. She's the most mature too..]
Caren: Born on the later side of midnight on Friday, February 14. Caren has stated she is 18 years old in chapter 12 of the manga. February 14 occurs on a Friday in 1975, 1986, 1992. Out of these, Caren's birth year is most likely choice is 1986 since the manga is published roughly in the same time as summer 2003.
Noelle: Born on the earlier side of midnight on Thursday, February 13. Since Noel and Caren are twins, the same logical reasoning applies to Noel in conclusion that both their birth years are 1986.
Coco: Born Tuesday, August 7. Coco is shown as a young women in a flashback of chapter 17 in the manga and about the same time, Lucia is still a little girl. Therefore we can conclude that Coco is at least older than Lucia. August 7 occurs on a Tuesday in 1973, 1979, and 1984. The best guess would be 1984, since Lucia's year is 1989. [This makes her about 20.. she sure doesn't look that old..]
Sara: Born Sunday, November 22. Sara is at least older than Lucia [my logic because she was in a relationship with Taro. She must've been pretty mature by then to be in a relationship like that. Hence when it ended, she killed Kaito's parents, so we at least know that she is older than Lucia] November 22 occurs on a Sunday in 1970, 1981, and 1987. The best guess here would be 1981 [making her about 22 in time of the anime/manga]
Siera: Siera was born on a Sunday. [All Orange Pearl Voices are born on Sunday] From Pearl Song, the guess was the day after Christmas, December 26. 2004. *
*Although not listed in the fortune telling book, I did find her birthday guess on Pearl Song.