Did you see? How she only reacted when she saw my face. [It's as if he's implying that he did it. But no, he's not done.] As it turns out, if you were taken in from the wilderness, there had to be someone who left you in the wilderness.

[Then he tilts his head to look directly at Kiryu.]

And you had to come from somewhere-- a somewhere that had another child, so that somewhere did not feel conflicted about throwing you away.

[He is indeed implying that he had a sibling-- and said sibling was the one responsible for this.]