Jean

Jan is curious, brave and intensely loyal to Leo. His interest in strange incidents initially resembles a child's enthusiasm for investigation, but he continues searching even when the danger becomes real.

He is also stubborn enough to challenge Allen Walker's conclusions when they threaten his belief in Leo. Once confronted with the truth, however, Jan prioritizes his friend's trapped soul over his desire to keep Leo beside him.

Jan is an ordinary human and has no Innocence or supernatural combat abilities. His strengths are persistence, curiosity and a willingness to investigate suspicious incidents despite his age.

His encounters with Akuma leave him dependent on Allen for actual combat. Jan's importance comes from his relationship with Leo rather than physical power.

Jan and Leo investigate reports surrounding Akuma, eventually bringing them into contact with Allen Walker. Allen's cursed eye allows him to perceive what Jan cannot: the human soul imprisoned inside the Akuma using Leo's appearance.

Leo had attempted to resurrect his mother through the Millennium Earl and was killed when the resulting Akuma took his body. After Allen reveals the truth, Jan asks him to destroy the Akuma and release his friend's trapped soul.

Jan subsequently becomes associated with the Black Order, though he does not become an Exorcist.

Leo is Jan's best friend and the person he refuses to abandon. After learning that the real Leo's soul is trapped inside the Akuma wearing his body, Jan asks Allen to exorcise him rather than leave Leo imprisoned.

Allen Walker reveals the truth about Leo and protects Jan from the Akuma. The encounter teaches Jan what Akuma actually are and why destroying them can also mean saving the souls inside.