IU is an A-Class national secret in England. In Japan, it is an I-Class State Secret. If authority gained knowledge of your involvement in IU, even just knowing about them, you will be pursued by Public Peace Zero Division or an Armed Prosecutor. Since merely knowing about IU may put one's life in jeopardy.
In IU, everyone is a teacher, and at the same time, a student as well. IU is a place where prodigies congregate, and share their skills with one another, extending their limits further. Infighting within IU may be common since they do not prohibit it within their organization. From what little that has been told and shown, IU appears to be an amoral secret society whose goal is to continually push, and eventually surpass, the limits of human evolution. The members of the society are usually free to pursue whatever methods they feel are most effective, but all members must defer to the society's senior leaders. Examples of such different methods include the coercion of powerful humans into serving as pawns or members for IU and genetic experiments with the goal of improving the human condition. It is possible that IU ultimately aims to create a superior being comparable to a deity.
I —— The Imperial Japanese Navy's designation for a submarine.
U —— The Kriegsmarine, or WWII-era German Navy, designation for a submarine.
IU's hidden form is that of a submarine. Known as one of the greatest strategic nuclear submarine in history, "Vostok" it is 300 meters long. It was stolen by a man who possesses the greatest brain in history, known as the "Profession". The name IU had come from the codename for submarine's during the World War 60 years ago, the submarine itself had come from Russia, 30 years ago. A submarine that had been stolen from the former Soviet Union. Also, it is said that IU can destroy a country in a matter of seconds without being noticed.
As revealed by Akari Mamiya, IU assaulted her family's household killing many and forcing the survivors to go into hiding.
In Volume 5, IU has been destroyed following the defeat of Sherlock Holmes. The following power vaccuum has caused the world to teeter into a looming war.
- Sherlock Holmes (Leader, incarcerated)
- Vlad / Sayanaki (Rank #2 in IU)
- Katze Grasset (IU's Commander-in-Chief)
- Patra (Former #2 and IU's Ignatius)
- Kinichi Tohyama (Kana) (Undercover Double Agent who is, in fact, trying to destroy the organization)
- Kyouchikytou (Former Member)
- Suimitsutou (Anime only)
- Riko Mine (Former member)
- Jeanne d'Arc (Former Member)
- KoKo sisters (Ranban Mercenaries and Explosive Experts)
|Butei||Butei Law • Butei Ranks • Butei Academy Uniforms • Team Formations • Caravan • Amica • Quartet • Lumberjack|
|Butei Curriculum||Assault • Lezzad • Connect • Inquesta • Logi • Medica • Research • Intern • Masters • Colt|
|Powers and Tools||HSS • Irokane • Stealth • Fuchou Poison|
|Locations||Tokyo Butei High School • Hotogi Shrine • Nagoya Butei Girls Academy|
|Organizations||IU • Bandire • Ranpan • GIII League • Regiment Hex • Kinokuni • Public Division 0|
|Families||Tohyama Family • Mamiya Family • Ulus Tribe • House of d'Arc • The Cao Clan|