Strength in Numbers is a free introductory scenario for Teenage Demon Slayers. Introductory scenarios have a lot of goals that they have to fulfill. They have to give the basics of the system, establish a tone, and make us want to come back and play more. Strength in Numbers fulfills all of these, and even has a few innovations that you might not expect.
First of all, though I'm not sure if it's intentional, the scenario sets a very serious tone. For a game about teenage demon slayers, the demonic problems and damage is presented absolutely straightfaced and without winks and nods. This is interesting, and something that I've often found helps comedic games - if the comedy lies in the characters, Buffy-style, then the situations have to be "real" in order for the game not to go crazily off the rails into nonsense. The Strength in Numbers scenario is presented with almost a grim tone, counting on the concept of the game and the players to provide any levity. That's a good choice.
A second unusual trait of Strength in Numbers is its timeline. Although many mystery scenarios are constructed around a timeline, Strength in Numbers gives specific time segments for different actions the player characters might try, such as questioning witnesses or pursuing suspects. This helps new GMs follow the timeline of the evil demon-summoning delinquents, a good tool for an introductory scenario.
A free scenario like Strength in Numbers is a great idea for any game, especially for cheap bastards like myself, and Strength in Numbers is a good way to get started with Teenage Demon Slayers!