Tenka Goken

The Tenka Goken (天下五剣, Tenka Goken) are a group of five extraordinary Katana. Proposed after the termination of the automaton research, it was an attempt by the Anti Katana Crime Division to utilize the core of a Katana, Hihiirogane, as a weapon as well and create their "ace in the hole". However, the plan backfired and they were sealed away. Eventually they would resurface, now employed by the Artisans.

Overview
The Tenka Goken are different from other Katana in the sense that they possess unique parts. This includes some sort of amplifier that raises the synchronization rate between the kenshi and the Katana. According to Jūzō Tsukiyama, each of the Tenka Goken possess special armaments, allowing them to easily take their pilot's lives. He refers to them as "demonic" or "cursed" swords. The Tenka Goken cannot be piloted by regular humans - they require a strong soul that wouldn't be lost even if torn apart and a combative spirit that surpasses human knowledge.

History
The Tenka Goken were joint developed by three private companies, due to demands by the government. These were Kamibishi Heavy Industries, the Sakuma Corporation and Torii Tech. Although it is believed they were permanently disposed of due exceeding the capacity of a normal human soul, the Tenka Goken were actually stored in a research center's warehouse due the amount of money that had gone into them. However, before that could happen, both the Katana and the swordsmiths in charge of managing them disappeared.

List of Katana

 * Dōjigiri
 * Juzumaru
 * Mikazuki Munechika
 * Onimaru
 * Ōtenta

Behind the Scenes
The Tenka Goken are an actual group of swords forged by famous swordsmiths, made famous during the Muromachi Period of Ancient Japan.