Toaru Majutsu no Heavy na Zashiki-warashi ga Kantan na Satsujinki no Konkatsu Jijou Manga Chapter 001

An Otherworldly Battle that Begins with Kamijou Touma's Usual Misfortune (上条当麻のいつも不幸から始まる異世界バトル) is the first chapter of the Toaru Majutsu no Heavy na Zashiki-warashi ga Kantan na Satsujinki no Konkatsu Jijou crossover manga, released on February 12, 2015.

Synopsis
Touma runs up to a bit of misfortune again when his toilet goes haywire. As he tries to fix he discovers that his entire world, or rather, he is transported into another world or dimension. Upon his feet are wooden boards, above his head is a shining blue sky and far off into the distance, pyramid-like mountains rise up on the horizon. Despite the sudden change of scenery, Touma is more concerned about his toilet. His troubles are multiplied however when he comes upon and indecent Index, and Misaka Mikoto as well comes upon them as well.

The two are angry at him but before they could punish him a large "Object" appears. It is Baby Magnum of the Heavy Object series, piloted by Milinda Brantini. Also, accompanying her not far off, is Quenser and Heivia, two hapless foot soldiers. As they wonder where they are a dragon appears and attacks the Object, to which Milinda retaliates, though the dragon is surprisingly reselient. Quenser and Heivia are worried but they end up into an argument. Unbeknownst to them (including Milinda), a shell from the Object richocet's from the hide of the dragon and toward the two. They would have been killed if not for the timely arrival of the Zashiki-Warashi, Yukari, stopping the shell with the palm of her hand--she immune to physical attacks. While Quenser and Heivia cower, Zashiki-Warashi turns aside to find the Yuki-Onna straddling Jinai Shinobu. Yukari asks the girl to turn her attention to dragon, though she is unperturbed, quickly freezing the dragon (along with Shinobu) momentarily ending the threat.

Meanwhile, Ansai Kyousuke and Higashikawa Mamoru of the Simple series, monitor the situation and comments on how they have been pulled into another absurdity. Much to their horror, the source of their terror from their series appear before them, Bunny Girl Karen, asking them not to blame her this time. They quick;y flee at the sound of her voice, and she gives them a chase with glee. Also, not far off observing all of them is the Killer Princess, Satsuki, as well as Nanajou Kyouichirou, the latter notes that he wants no part of what was happening. Satsuki adds that she may not be able to kill any of the non-humans present there, to which Kyouichirou adds that he also wants no part of her as well.

All is not well however as the dragon rises up again, much to Yuki-Onna's annoyance. All of a sudden, a pillar of water shoots out from one of the "mountains" in the distance and hits the beast. It rolls away, finally ending the threat. In the distance, Waltraute and Jack Elvan observe the strangers from distant lands.

Adapted from

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

Major Events

 * Touma's apartment is transformed to allow characters from Kamachi Kazuma's work to "crossover". Index and Misaka Mikoto is dragged along as well.
 * Touma, Index, and Mikoto meets a bunch of inexplicable people and survives an attack from an actual dragon courtesy of Waltraute.

Toaru Majutsu no Index universe

 * Kamijou Touma
 * Index Librorum Prohibitorum
 * Misaka Mikoto

Heavy Object universe

 * Quenser Barbotage
 * Heivia Winchell
 * Milinda Brantini

The Zashiki Warashi of Intellectual Village

 * Yukari (Zashiki-Warashi)
 * Yuki-Onna
 * Jinnai Shinobu

A Simple universe

 * Anzai Kyousuke
 * Higashikawa Mamoru
 * Bunny Girl Karen

Killer Princess and the Deep End

 * Satsuki
 * Nanajou Kyouichirou

The Circumstances Leading to Waltraute's Marriage

 * Waltraute
 * Jack Elvan
 * Hel (chapter image only)

Abilities

 * Railgun (ability) - Misaka Mikoto, Level 5

New Abilities

 * Zashiki-Warashi powers - Zashiki-Warashi
 * Yuki-Onna powers - Yuki-Onna
 * Valkyrie powers - Waltraute
 * Pillar of Water attack

Locations

 * Academy City
 * School District 7
 * Kamijou Residence

New locations

 * Waltraute's world (unnamed)
 * Skíðblaðnir (unnamed)

Trivia

 * This marks the appearance of an actual dragon in the series.
 * This marks the appearance of an actual Valkyrie in the series.

Unanswered Questions

 * How did they end up in that world?
 * What happened to Touma's room?
 * How is Touma affected by this?
 * Where did that dragon come from and why did it start attacking?

Quotes

 * Yuki-Onna: "Anyone who interrupts someone's love deserves to be frozen in ice."―after freezing the dragon.
 * Mamoru: "Don't turn around! We have must have been thrown inside a space where looking back is forbidden!!" ―to Kyousuke as they are being chased by Bunny Girl Karen.