A recent article on Mantan Web profiles the rapid growth of the Dagashi Kashi manga by Kotoyama, which has doubled its per volume circulation in the less than 4 months leading up to the debut of its TV anime adaptation.
According to the article, when the TV anime adaptation was originally announced in September of 2015, the first 2 volumes of Dagashi Kashi had sold about 450,000 copies total and were averaging about 200,000 sales per volume.
As of the publication of the 4th volume in December of 2015, these numbers had swollen to about 1.2 million total copies sold.
As of the airing of the 1st episode of the Dagashi Kashi TV anime on January 10, 2016, sales had increased to about 1.6 million copies total, with each volume averaging about 400,000 copies per volume. Official sources cite interest in the TV anime as the driving factor for the surge in sales.
The Dagashi Kashi is serialized in Shogakukan's Weekly Shōnen Sunday manga anthology magazine, and 4 collected volumes are currently available in Japan. The Dagashi Kashi TV anime is being simulcast in North America by Funimation.
Paul Chapman is the host of The Greatest Movie EVER! Podcast and GME! Anime Fun Time.