The tragedy of Sogetsu Castle is the first book I read from author Masayuki Kagami.
A group of people are invited to stay in a castle which is owned by a pair of beautiful twin sisters from a noble family. Then one of the twins is killed and beheaded in a locked room high up in a tower, so...what's next?
PS: the simplified Chinese translation is a piece of shit, so many obvious wording mistakes here.