Japheth is the Crown Prince of the Empire of the Seraphim.
Japheth is the crown prince and a legitimate child of Joram. Unlike his warrior half-siblings, Japheth is a coward who, in Akiva's words, would rather not be involved in a war even if he was not fighting in it himself. Japheth "was a soft skulkling, afraid to leave the Tower of Conquest even under full escort."
Japheth became the crown prince after his older brother murdered their oldest brother and was murdered in return right after committing the crime. The oldest brother was Avenged while the older brother was remembered as Unshrived.
Days of Blood & Starlight
Japheth is mentioned during Akiva's plan to assassinate Joram. Since he is the crown prince, he would take the throne after his father's death, and, if things went accordingly, the war would end with his rule. In the aftermath of Joram's assassination, Japheth is crippled by fear and tries to use a serving girl as a shield, further proving his cowardice.
After Akiva announces Japheth to be the new emperor, Jael returns with soldiers and kills his own nephew to become the new emperor himself.
•In the bible, Yefet (the correct transliteration of Japheth) was the son of Noah.
- Days of Blood & Starlight Chapter XX, pg. XX