件

くだん

no-adjective

the aforementioned, the said, (man, incident, etc.) in question, the above-mentioned, the aforesaid(usually kana)

the usual

件	affair, case, matter, item

とき

、

くだん

ふたり

とうこう

Just then the two in question arrived at school

くだん

ななふしぎ

はなし

。

しら

This is about the case of the "seven mysteries". Did you investigate it