No firm dates can be assigned to this emperor's life or reign. Chūai is regarded by historians as a "legendary emperor" because of the paucity of information about him, which does not necessarily imply that no such person ever existed. Rather, scholars can only lament that, at this time, there is insufficient material available for further verification and study. If Chūai did exist, there is no evidence to suggest that the title tennō was used during the time period to which his reign has been assigned. It is much more likely that he was a chieftain, or local clan leader, and the polity he ruled would have only encompassed a small portion of modern day Japan.
According to the Kojiki and Nihonshoki, he was the father of Emperor Ōjin. Ōjin is generally accepted to have existed based on archaeological evidence, but his father was Yamato Takeru, whose story is generally accepted not to do so. He was a grandson of Emperor Keikō, a Yamato monarch. Chūai's wife was Jingū.
According to these same legends, his wife was suddenly possessed by some unknown gods. The gods promised Emperor Chūai rich lands overseas. Chūai then looked to the sea, but he could see nothing and denounced his belief in the promises of the gods. The gods were enraged by this and declared that he would die and never receive the promised land. Instead they would go to his conceived but unborn son. The legend then states that Chūai died soon after and his widow, Jingū, conquered the promised land, which is conjectured to be part of modern day Korea. According to one version of the legend, Chūai's son was born three years after the death of Chūai, which lends further support to the notion that the stories surrounding him are based on myth rather than actual events. This legend also has many other flaws (it claims that Jingū was flown into the middle of the promised land and then conquered into Japan) which have largely discredited the story among historians.
As part of the Cloverfield ARG, an oil platform was named Chuai, possibly after the Emperor.