Class : Mashin (also known as "Rune God") [means magical god]
First Appearance in : 
Episode 10
Name in Spanish dub : Seres (also spelt as Zeres)
Name in Portuguese dub: Ceres
Corresponding car name : Toyota Corolla Ceres
Japanese Voice Talent : 
Genda Tessho
English Voice Talent : Terrence Stone
Songs sung by Seresu : None
Rayearth's Description
Seresu is one of the three legendary Mashin of Cefiro.  The legend goes something like this:
"When the pillar of Cefiro has altered,
the people who were summoned from the 'other world',
will become the legendary Magic Knights,
and fight with the help of the Mashin."
However, awakening the Mashin are not that easy, you must first have a weapon made of Escudo and take a test until the Mashin will recognize your power and the ability to control him.  For Seresu, Umi had to choose between running for her life for the greater cause to defeat Zagato (that's what Seresu tells her to do) while leaving her friends behind for Ascot to hammer them or die trying to save them.  Seresu was the first of the three Mashin the knights awakened.
Facts about Seresu
Seresu is described as "sea dragon" when he wasn't in his Mashin form, but he actually has wings.
Seresu has dragon/bat like wings and a tail dragons have.
Although Seresu has many names, his symbol conveys that his name must start with an 'S'.
Seresu is my favorite Mashin ^^