Secchan is usually rather timid, so her sudden outburst comes as a surprise. Besides, little Taku was a lot more expressive and less... indifferent seeming than he is nowadays.

Setsuko: "Because Hideki told me that Rumi's big sister was killed there too. I thought he just wanted to scare me... so I looked it up, and... he didn't lie. It really happened."

Suddenly, Setsuko shouts Taku's name with a serious expression, which startles him a little.

Taku: "W-What?"