Grandma and great grandma are the biggest losers and pieces of molten and rotten turd there. They began all that shit that you'll fail if youleave town all because, please make me remember if i'm wrong, but iirc,it was either Yuko's gma or great-gma who went to Tokyo to try out as an actress, but failed miserably and saddled the Kurose bloodline with a generational debt.
All her misery was passed from gen to gen. Yuko had a glimpse of hope into Akira, however, he wasn't able to read the signs, hints and room back then and ended up pushing her to the point of not return.
Stillo
that shit doesn't excuse Yuko from everything she did to Gen, his bro and Reiji, but this is a nice example on how victims became perpetrators when they lose hope. That laughter is a post traumatic reaction after being let down, left behind and ashamed by her only light. All hope was lost for Yuko since then.
And even if Reiji didn't choke her, shoving a patient who's connected to lots of IV tubes isn't a good idea and his timing was the worst ever tho.
Yuko remembered the shit that was done to her, just as Reiji wished (but he doesn't know yrt, and may get a wrong picture of her laughter). Let's hope if she remembers all the things she did to ReiGen and Kazumaza so we can finally have the mom-son closure.