Harsh, cruel, brutal, extremely powerful and skillful as a warrior. Real butcher. He  killed every single person in country of Hi (Fire) followed by order from Himiko-sama. But after he met Nagi something changed him. In past his clan was annihilated, he is only survivor. Has been taken to Yama Tai Koku.     His name consist of three kanji: 猿 monkey (saru) 田 rice field (ta) and 彦 boy (hiko - actually very old one). Maybe it's mean nothing but it can help understand in some way his personality. 

Hi no Tori is a collection of stories that all have something in common. The Phoenix, whose blood is believed to give an eternal life to one who drinks it. Therefore many seek to kill it, but as the Phoenix of the tale, it's reborn from the ashes. Stories take place in future and the past, where humans fight with each other as always, and everyone is afraid to die. But still, every story teaches a lesson: Life is beginning of an eternity, an never-ending cycle. <br><br>
(Source: Anime News Network)

Hiko Saruta