The Toaru Majutsu no Heavy na Zashiki-warashi ga Kantan na Satsujinki no Konkatsu Jijou (とある魔術のへヴィーな座敷童が簡単な殺人妃の婚活事情,A Certain Magical Heavy Zashiki-Warashi Deals With a Simple Killer Princess' Marriage Circumstances?) manga is an adaptation of the crossover novel by Kamachi Kazuma of the same name, and is published in Monthly Shōnen Gangan. It is the sixth manga based off the Toaru Majutsu no Index universe and the 4th one to be published in Monthly Shōnen Gangan. The structure of the manga was done by Nishino Ryuu and was drawn by Fusemachi Hajime. Serialization began on February 12, 2015.
The crossover novel was part of the 10 Year Anniversary Celebration of Kamachi Kazuma's work. Part of this anniversary was the release of animated short featuring characters from the author's work. Many of the characters appearing in the animated short would later reappear in the novel as well, and in turn in the manga, making the short a pseudo-trailer for the novel and manga.
The manga would mark the first time many characters from novel series and stories, apart from Toaru Majutsu no Index and Heavy Object, would be appearing in manga form.