Ah, yes! I was worried Lulu will act just like Yurika. Don't repeat the mistakes of the adults, kids!
Ginko became a different person from when we first met her until chapter 10-12 happened. And her personality turned upside down. From normal, happy high school girl turned to cold person.
Well, she remembered a tragic event from the past. How could she still pretend to be happy when she knows her mother killed Kureha's mother and now she is scared of the thougth she can do the same to Kureha?