He is one of the characters of Shugo Chara and is introduced in Episode One.
His Chara is called Yoru. Yoru has yellow cat-like eyes, blue hair and has blue ears. When they Character transform, they are called Black Lynx.
Ikuto has a younger sister called Utau Tsukiyomi, who has a MAJOR brother complex/ wants to be his girlfriend, but she gets over that stage.
Ikuto met Amu Hinamori in episode one, and has teased her to bits since them.
Ikuto said he liked her in chapter 31 of shugo chara (Maybe 32, not quite sure) and she brushed him off as joking, but we all know she loves Ikuto. (:P to Tadamu followers)
Ikuto also loves to tease Tadase Hotori, Tadase use to call Ikuto, "Oni-tan" when they were younger but now, Tadase thinks of him as his mortal enemy, espicially with Amu.
He is under the control of Easter, and they are using him, making him turn into Death Rebel during the 33rd Chapter.