Ken J. Tanaka, known as The Tactitian and Smoke and Mirrors, was the Seventh Emperor (Imperator Septimus) of the Empire. He was the father of Jeremy 'Kaiju' Tanaka. He wielded the Aoge's Cloning (VIII) and the Akage's Smoke (V).
Ken Jimura Tanaka was born in Capita, the Empire to the noble Tanaka clan. As the only son of the clan in some time, Septimus was lauded upon by his family during his childhood. He was tutored extensively by experts in the hope he would eventually lead his family. He was enlisted as a Soldier immediately after turning 14. As he wields two different Ge, he showed great effectiveness in field missions. He was also considered a tactical genius. Later on, he married fellow Brigadier Lou Leitre and they had their first child, Jeremy, three years on from this (Emergence, Destinies).
Septimus was ordained as a Master by Sextus a month prior to The 5th Great War (Metal City, Destinies). His wife was among the first casualties. He designed the tactics to undercut the Republic's numbers. Septimus was named the Emperor following the death of Sextus, naming Ijuiin Kokoda, Genbu Akasha and Oki Ishido as Masters.
When the Republic threatened the elimination of Kaiden, he gave the order to soldiers living there to "risk their lives to stall the enemy" (Induction, Empires). Soon after the war he agreed to lock Oki in the Empire Prison as his power had become uncontrollable, however refused to remove his title of master (Emergence, Destinies).
When Jeremy turned 17 he was implicated in the murder of a noble. Soon after his imprisonment, he escaped and ran away with the help of Shon Lee (Emergence, Destinies). The news was hushed up by Seven to prevent the Republic taking advantage of it.
Septimus' main personality trait was that he lacked any empathy. He believed that emotions clouded his judgement, and avoiding them allowed him to make moves more efficiently when the time mattered. Whilst negatively impacting him, in that his son would abandon him after being alienated (Emergence, Destinies), it was for this reason he was requested by Sextus to be ordained as Emperor (. This was fulfilled when Septimus gave the order to the soldiers of Kaiden to sacrifice themselves to stall the enemy, ultimately saving the lives of the town's inhabitants. Many viewed him as evil, thinking that he used people as chess pieces, however this like many opinions were not noted.