Ken Ichijouji

Ken Ichijouji is a Japanese Digidestined. He is a protagonist in The Darkness Beckons and a supporting character in The Light Shines. Originally intended to be a member of the original Japanese Digidestined, he ended up traveling to the Digital World on a different occasion with Ryo Akiyama.

He was the Digimon Emperor, but since atoned for his sins. He later became the Marshal and eventual Supreme Commander of the Gennai Army. He was also the commander of the Fourth Division. He was later a leader of the Terrestrial Gennai Army, the mastermind behind The Plan and is considered one of the Three Legendary Warriors.

For a short time, Ken was "undisputed Digimon King" before the title expired.

Background
http://digimon.wikia.com/wiki/Ken_Ichijouji

Origins
After defeating Milenniummon with Ryo Akiyama, he was infected with a Dark Spore that made him evil. After the battle, he knocked Ryo down while commanding Stingmon to take down Monodramon. By defeating Ryo, Ken inherited his title as "undisputed Digimon King." Ken then imprisoned Ryo in the Digital World and left.

During his time as Digimon Emperor, Ken was knocked down by Takeru Takaishi, arguably giving TK the title he inherited from Ryo. Of course, most claim the title dissolved after Ken lost his position as Digimon Emperor. Also, since Malomyostismon technically defeated TK (with his illusion) and then Imperialdramon defeated Malomyotismon, it is possible that Imperialdramon is the Digimon King.

When Ken was purified from the evil in his heart, the evil infected seven Digi-Eggs, creating the Seven Great Demon Lords.

Beelzemon Crisis
During the events of The Light Shines, Beelzemon impersonated Ken in order to manipulate Hikari Kamiya and capture TK. During the battle with Beelzemon, Ken was nearly killed, but was later came through. At the end of the story, Ken began a relationship with Miyako Inoue.

Kari Crisis
When Daemon captured Kari, Ken went to investigate and became a central protagonist in The Darkness Beckons. He finds that Liu is Gennai and goes to the Digital World to become the Marshal of the Gennai Army.

Third Digital World War
After Ken botches the defense of Gennai's House, the aquatic Digimon attempt to overthrow him. When Michael Washington decides to reaffirm his faith in Ken, Ken splits the army into six divisions and orders an attack on each of the six surviving Demon Lords.

After leading the Fourth Division against Barbamon, Ken groups his army with the rest of the divisions for the Charge on Hell Hill. After Gennai dies, Ken became the Supreme Commander of the Gennai Army.

Digidestined Civil War
Upon returning, Ken, TK, and Daisuke Motomiya are spared while the rest of the Digidestined are captured by the International Digidestined Alliance. Ken then conives The Plan to defeat the Alliance and travels to London with Terriermon and Lopmon.

While in London, Ken secretly meets with anti-Alliance Digidestined in order to plan an attack on the Alliance. He secretly travels to Dublin, Ireland, but is ousted by Alliance loyalists among the Irish Digidestined. Many of Ken's allies are captured during the Battle on the Liffy and Ken retreats to London, losing a lot of credibility.

After the incident in Ireland, Ken is ousted to the world. He begins traveling Europe as the Ambassador for the Gennai Army on Earth and begins recruiting some of the European Digidestined to join the rebel group.

On a trip to Paris, he meets Gilbert d'Mars, the leader of the French resistance. After escaping Catherine Denevue and Edouard Valois, Ken returns to London to find that Alistar Bure has declared all British Digidestined at war with the International Digidestined Alliance.

Catherine leads the Alliance loyalists on an attack on London, where they meet Ken, Alistair, and Gilbert who repel the loyalists from the British Isles during the Battle of Southend-By-The-Sea.

After the battle, Ken travels to the North Sea Prison and frees Yolei, Iori Hida, Willis Thompson, Hawkmon, Armadillomon, and Wormmon.

After freeing them, Ken and the Gennai Army of Europe travel to Japan in the invasion of Japan.

Ken, Stingmon, Yolei, and Aquilamon fight the Battle of Highten View Terrace by air.

After the war, Ken disbands the International Digidestined Alliance in an address to the United Nations General Assembly, then joins Yolei for a trip through Paris.