See this is why I why I said Seiko reminded me of Sangwoo's mother from Killing Stalking she also got jealous when her son received a love letter. I was hoping it wouldn't go that route but the emotional incest is undeniable at this point. Now I'm just holding hope that it doesn't cross the line of actual incest. I feel so bad for Sei you could tell that he actually did wanna go out with her. He looked so happy when he read that she loved him for longer than a year. But I could already tell his mother wouldn't be OK with this she looked ill and jealousy stricken before even reading Note. But I was still suprised to see her vocalize it.