Volume 18 of Gotoge Koyoharu’s Demon Slayer: Kimetsu no Yaiba will be published on 4 December with a print run of 1 million copies. Including digital copies, the series will surpass a total of 25,000,000 units in circulation.

To commemorate this achievement, Shueisha will carry out a new campaign called ‘The Most Merciful Demon Exorcism in All of Japan’ (これは、日本一慈（やさ）しい鬼退治). Posters have been designed containing dialogue and expressions brimming with the love and kindness of 18 different Demon Slayer: Kimetsu no Yaiba characters, and will be displayed in downtown Tokyo/Shibuya, Osaka City JR West Stations, Nagoya Subway Stations and Fukuoka Nishitetsu main stations.

Major bookstores across Japan have been giving customers who purchase titles related to Demon Slayer: Kimetsu no Yaiba ‘original cards’ that use the same illustrations as a gift to go along with their purchases. An online campaign will also be carried out via Twitter, so you can get a picture of your favorite character! The campaign will start on 1 December at 00:00 and will finish on the 31 December at 23:59 (JST). During this time period, you just need to add the following 3 things to your tweet:
1) Tag the official account @JCkimetsuCP
2) Add the hashtag #日本一慈しい鬼退治
3) Write a hashtag with the full name of your favorite character in Japanese. For example #竈門禰豆子
If you do these three things in your tweet, you will receive a reply with a picture!

source: https://natalie.mu/comic/news/357098
translator: nifa