The great King Imuka was the ruler of the Dominion of Agustria, and strived for peaceful coexistence with Grannvale more than anything. After Sigurd's retaliation against and subsequent subjugation of the neighboring Kingdom of Verdane for invading Grannvale, the political situation in Agustria was becoming more unstable. The Lords of the Dominion expressed strong anti-Grannvaleian sentiment, and with Sigurd's forces stationed at Evans Castle, the country was on edge.
King Imuka was suddenly killed by an assassin under dubious circumstances, and was promptly succeeded by his eldest son, Chagall, who favored war with Grannvale. With many of Grannvale's best troops occupied far to the east due to the conflict with the Kingdom of Isaach, Chagall quickly seized the opportunity to command the Lords of Agustria to invade Verdane and defeat Sigurd's forces.
According to an Agustrian villager, King Imuka was considered a "great soul", and was much loved by the people. He was also known to show great favor to Eldigan. It is later revealed that it was Chagall who killed Imuka at the urging of Manfroy and the Loptyrian Cult.