二銭銅貨

This is Edogawa Ranpo's first work, and highlights the kind of intricate tricks he's often known for, in this case a very interesting cipher. The story is broken into 3 sections. I found the second section a bit less interesting, but there are some good details in there that made more sense after the reveal.

I read the story along with this 朗読, which made it a lot easier to follow along. I enjoyed the story, and the dynamic between the characters is fun. (they're probably not friends anymore after this, lol.) There are slightly older kanji and grammar used throughout, but it was published in 1923 so it's nothing too old. It also references some things that would have been familiar to people at the time, but are uncommon now, so be ready to google a few terms that won't be in jmdict.