Ultraman Gaia & Agul (1998–1999)

Ultraman Gaia takes place in yet another universe, one that is totally different from the world of the original Ultramen. there are two Ultramen as the main characters (Ultraman Gaia and Ultraman Agul). They have conflicting philosophies in regards to defending the Earth from a mysterious, malevolent and extremely intelligent cosmic entity.
The first half of the series explores the growing tension between them, and their eventual clash. The second half has them reconcile their differences so they can defeat their common enemy.
In this series, Gaia is the lead, but Ultraman Agul makes many appearances. They are often at odds with each other in the beginning of the series. Their philosophies are as different as their skin colors. Unlike Gaia, Agul is completely blue. Takayama Gamu, the human host of Ultraman Gaia, believes that Gaia is here to save Earth and humanity. On the other hand, Fujimiya Hiroya, the human host of Ultraman Agul, believes Agul to be Earth's natural defence mechanism. He is at first more interested in protecting just the planet itself, even at the expense of humanity (hence the occasional clashes with Gaia).