The moment Eiko appeared on screen, I had a strong feeling she was the nurse—just with a new, shorter haircut. And when Osanai brought up that one of Eiko’s options had been to kill Kobato, she tried to deny it... but didn’t she already run someone over and flee the scene? It feels like a major twist is still on the way.
So far, we have Eiko Hisaka (who’s actually the nurse), Shotaro Hisaka, and the man who falsely posed as Shotaro’s father. Then, right after that revelation, the news drops that someone has been arrested for the hit-and-run and other related crimes.
Shotaro’s reaction to Kobato uncovering the truth about his fake father was anything but pleased. From the way the Hisaka family has been behaving, it's obvious they don't want the investigation going any further. It definitely feels like a messy family situation—maybe involving step-siblings, half-siblings, or fallout from a divorce. And whatever went down in the past, it seems like Kobato is being made the scapegoat.