Ceres

Ceres is a Rune God and one of the three legendary guardians of Cephiro. Ceres first appears in the form of a large blue European-style dragon. Ceres is in fact an ancient mecha used by the Magic Knights to help them combat Zagato and ultimately kill the Pillar. Ceres is paired with Umi Ryuuzaki. (Source: Magic Knight Rayearth Wiki)