Toaru Majutsu no Heavy na Zashiki-warashi ga Kantan na Satsujinki no Konkatsu Jijou

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) is a crossover light novel by Kamachi Kazuma featuring characters of all of his novel series including Toaru Majutsu no Index. It was announced as part of the Kamachi Kazuma 10th Year Anniversary Celebration. A preview of the story was released in Dengeki Bunko Magazine Kamachi Kazuma BOX booklet released on November 25, 2014, and previews of the color illustrations were released in Dengeki Daioh Kamachi Kazuma 10th Anniversary Illustrations Compilation Illustrations booklet. The full release features art from several artist including Haimura Kiyotaka, illustrator for the Toaru Majutsu no Index light novels.

It was later revealed that the story would be inspiring a manga series, to be released in Shonen Gangan starting from February. A 30 page preview was later shown on the Dengeki Bunko website prior to the book's official release.

Illustrations
Cover illustration: Nagi Ryou

Frontispiece and text illustrations:

Haimura Kiyotaka · Nagi Ryou · mahaya · Kasai Shin · Ikawa Waki · Karasuma Wataru · Inue Shinsuke · Asakura Ryousuke · Taishou Tanaka · Hara Tsumoi · kamada

Publisher's summary
Kamachi Kazuma 10th Anniversary! A large gathering of Kamachi's characters are set to make a novel appearance! Moreover, the adaptation of the story will be in Gangan Comics starting on the same month!!

One day, Kamijou Touma awakes to find a strange space in his room. There is also the mystery of the huge weapons called "Object" that has been fighting with a flying dragon, a shotacon fantasy Oneee-san giving her aid, wandering together with Mikoto who is wearing bikini armor....A large gathering of popular characters and heroines assemble from Kamachi's works to form a special novel!

Dengeki Daioh appendix booklet has all the illustrations! The Kamachi Kazuma BOX has the first part of the story and now the full version has now been released. List of works: Toaru Majutsu no Index, Heavy Object, The Zashiki Warashi of Intellectual Village, The Marriage Circumstances of Waltraute-san, the Simple series, Killer Princess and Deep End, and others.