Seigi is a man with short dark-colored hair and a small mustache. He wears a uniform with a shirt and a tie underneath as well as a cap with a "sei" (正) kanji on it.
Not much is known of Seigi's personality but apparently he is a dutiful and honest man, much to the Prime Minister's dismay.
During the Revolutionary Army's uprising and the revolution gaining more and more support from both the Empire's citizens and foreign nations, it began to overwhelm the Empire's forces, the fact which Seigi reported to The Emperor. However, Prime Minister Honest claimed that Seigi was running away from his responsibilities by distracting the people with the news about the Imperial Army losing a war with Western nations.
Later, Syura suggested that he and his newly formed group Wild Hunt kill Seigi to prove their competence, however, Honest noted that it wouldn't be necessary as anyone disloyal to him would be eventually framed, driven from their position and executed.
- The kanji on his cap is apparently the shortening of his name, which can mean "justice" or "righteousness".