Illumi is Killua's eldest brother. He is an experienced assassin, whom along with his father was responsible for Killua's training and upbringing. During the Hunter's Exam, Illumi camouflaged his appearance and took upon an alias, using special pins to change his entire facial structure to the point where he can only be recognized by his voice. An oppressive evil aura about him makes even Killua fearful and wary whenever he approaches Illumi. This may be due to a needle implanted into Killua's brain by Illumi.
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