At AnimeJapan 2023, KADOKAWA announced Konosuba: An Explosion on This Wonderful World! will have a live special broadcast on March 28 featuring Rie Takahashi, the voice of Megumin, and Aki Toyosaki, the voice of Yunyun. The spin-off anime will premiere on April 6.
Konosuba: An Explosion on This Wonderful World! was originally a Kadokawa-published fantasy light novel series that ran from 2014 to 2015 with three volumes. A sequel series began in 2016 and released its second volume in 2019.
Like the main Konosuba: An Explosion on This Wonderful World! isekai series, which ran from 2013 to 2020 with 17 main volumes and two short story anthologies, the spin-off is written by Natsume Akatsuki and illustrated by Kurone Mishima. The series and its sequel are published under the Kadokawa Sneaker Bunko label and have received manga adaptations by Kasumi Morino.
Yen Press describes the light novel series as:
One year before a certain useless goddess and NEET extraordinaire hit the scene, Megumin, the “Greatest Genius of the Crimson Magic Clan,” is hard at work. Ever since a life-changing encounter in her youth, the young wizard has dedicated her every waking moment to the pursuit of the ultimate offensive magic, Explosion! (Well…every moment not spent hustling food from her self-proclaimed rival.) And while the big sister’s away, the little one will play. On a routine trip into the woods, Megumin’s little sister, Komekko, finds a strange black kitten. Little does she know that this cat plays a key role in unsealing a Dark God’s tomb…
Source: AnimeJapan 2023