During a live stream of the Majo Labo! program, it was announced that Kakusansei Million Arthur would receive an ONA adaptation. The series is based on the official 4-koma web comic and will span four cours, premiering in the fall. Kakusansei Million Arthur is a card-battle game rooted in the legend of King Arthur. One million individuals also claim this title, each wielding their own Excalibur. Developed by Square Enix, the game launched on iOS and Android in 2012, followed by PlayStation Vita and Nintendo 3DS versions in 2014. The comic, drawn by Choboraunyopomi (Ai Mai Mi), is based on the game. It began online publication in October 2014 and currently consists of 17 chapters.