十角館の殺人 [Jukkakukan no Satsujin] #1

This is the first volume of the manga adaptation of Yukito Ayatsuji's classic locked-room mystery novel, The Decagon House Murders. Published by Kōdansha in their Afternoon KC imprint, it follows a group of university students who travel to a remote island where a series of murders eerily mirror a past tragedy. The story is known for its intricate plot and homage to the golden age of detective fiction.