"You're looking for someone to do a mission for you, aren't you?" The boy says and then whispers, "So obvious..."
Kaito looks at the Duelist from head to toe, quickly assessing him. He could feel the air of self-confidence coming from the young man from afar, which is, as Lysandra pointed out, a characteristic of the Duelists, because even the novice adventurers of this world know how cruel this place can be and so they are not so confident, but not all Duelists who come from Earth understand this yet, so many die in the Heavenly Abode.
Also, it seems that this boy is the kind of Duelist who thinks he is in a game. All it took was for Kaito to look at his group for a bit for him to think that Kaito had a mission or a service to offer, as if Kaito was an NPC. Anyway, Kaito decides to take advantage of the boy's approach to try to get what he wants.