Coffin

Coffins (棺桶) refer to large mobile weapons that are controlled by the corpses inside, specifically that of an esper. Coffins are able to boost the powers of the espers inside them and are able to use them to great effect.

First introduced in Toaru Kagaku no Accelerator, they are manufactured and used by the DA to cleanse Academy City of "evil".

Etymology
Qiong Qi, Hundun, and Taotie are mythical Chinese creatures as mentioned in the in the . They are three of the Four Fiends in the book.

Principles
The Coffins uses "evil spirits" of the numbers to allow it to function. It is currently unknown what these are.

The mecha can strengthen the abilities of the espers inside of it based on their level, in fact it can even boost it to a Level 5 ability. The mecha or the corpse inside of it can somehow follow orders and is intelligent enough to rescue its allies.

Prototype
The first seen Coffin is the Prototype. It is large quadruped mecha, with one large sphere that acts as the eye and is where the corpse of Hitokawa Hasami. The mecha has two tentacle-like appendages on of its side. It has powerful legs and is able to leap from a large fissure.

Using Hasami's ability, Pyrokinesis, it can boost her Level 2 ability to that of a Level 4.

Qiong Qi
The Qiong Qi (窮奇) is a large Coffin that uses a strengthened Psychokinesis ability equivalent of a Level 5. Unlike the more machine-like Prototype, the Qiong Qi is much more streamlined and animal-like in appearance. It has a head where its eyes are located, four legs, and two arm-like projections on its sides.

It is very powerful, able to dissipate Accelerator's wind attack. It is used to kill Nishio, mutilating his body and even melting his flesh. Similarly to the Prototype, it can make powerful leaps up to the sky. The machine is capable of injuring Accelerator even with Redirection, something he compares to that of Kamijou Touma.

Taotie
Taotie (饕餮) is a large Coffin that is much more rectangular in appearance than the other Coffins. It can fire both missiles and has two machine guns. It can leap high, though it has been shown to stay more on the ground. It has the Teleport power, allowing it to teleport objects, like its missiles, without touching them. It is later destroyed by Accelerator.

Hundun
Hundun (混沌) is a Coffin that is much taller than both Qiong Qi, and appears bipedal. It has several rockets that allow it to fly into the air. It also has several tendril-like appendages allowing it to grab objects. It was these that allowed Hundun to put a helmet on Misaka 10046, to allow data regarding her to be transferred to Hishigata's computer.