The anime, manga, and live action series of Kuzu no Honkai all finished airing this March, but the manga magazine Monthly Big Gangan, in which the last chapter was released, announced that it will serialize an extra story. Further details and news are scheduled to be published in upcoming Big Gangan issues.
Fans who purchase all volumes of the DVD/Blu-ray will get a color illustration as a present. If you order on Amazon.co.jp you will get a B2-sized cloth with Hanabi and Akane on it; from the Noitamina Shop, you get a B2-sized wall scroll with Hanabi and Sanae. There will be bonuses available at other stores as well, such a smooth B3-sized towel (image of Hanabi), a B1-sized wall scroll (with Sanae) and much more. Hunting down the best presents for yourself is a way to enjoy otaku life in Japan.
Finally, if you buy the DVD/Blu-ray you get the chance to buy event tickets before regular sales start. For more information, please check the official website (Japanese only).