Responses
I am calling it now, and I would bet money on it. Tanaka is Kurebayashi’s son. I love how their positions are juxtaposed like you pointed out.
What if the organization threatened to hurt Tanaka so she had to give Hikaru up. All she ever said was that her son was mixed, moved away, & didn’t like her much.
And a few chapters ago we learned that Tanaka knows her. His blindness and scar could be the “irreparable mixing/injury” of Iori that Ms. Kurebayashi mentioned.

NOO.. I liked Mrs.Kurebayashi, but I understand her motives. She seems empathetic, so I hope she may come to regret this choice later in the story.
The juxtaposition between her and Tanaka is interesting. Kurebayashi was initially presented as an adult whom the main characters can trust, while Tanaka was framed as an antagonist. Tanakas motives are still questionable, but its interesting how their roles have flipped (as of now).
If we are reading the connection between people and impurities as partly a queer allegory, this gives the presentation of their characters as initially trustworthy/non-trustworthy adults some layers...