Maruoka Castle, also known as Mist Castle, is a cool hirayama-style Japanese castle located in Sakai, Fukui Prefecture. Legend has it that a thick mist magically appears to hide the castle from enemies. Built in 1576 by Shibata Katsutoyo, it boasts the oldest tenshu (castle keep) in Japan, although there's some debate about that. The castle has a unique design with stone roof tiles and hidden windows for defending against attackers. Today, it's a public park with cherry blossoms galore, making it a popular spot for visitors to enjoy the scenery and history.