This episode is part of the arc.
The detectives, including Conan and Heiji Hattori (Harley Hartwell), use this paper to verify Hideomi's involvement in the ongoing murders at the Nagato estate. Detective Conan (Dub) Episode 77
The primary "paper" featured in this episode is a found in the pocket of Hideomi Nagato. This episode is part of the arc
This episode prominently features the first appearance of Heiji Hattori's rival/friend dynamic with Conan in a complex murder case. Miyuki. In it
The short note is addressed to Hideomi's girlfriend, Miyuki. In it, Hideomi apologizes for being unable to marry her due to his "sins" and claims that only death can cleanse him.