|Continuity||Dual! Parallel Trouble Adventure|
|Voice Actors||(Japanese:) Takayuki Yamaguchi
(English:) Jeremiah Freedman
|Age||16 years old|
|Occupation||Earth Defence Force|
|Relatives||Dual! series: Mr. Yotsuga, Mrs. Yotsuga, Zinv (Alternate Reality Conterpart)|
Kazuki Yotsuga is the main character of Dual! Parallel Trouble Adventure, an anime series canon to the official Tenchi Muyo! Ryo-Ohki universe.
Kazuki is a shy, quiet and awkward everyman except for the fact that he often sees visions of giant robots fighting each other. After writing about it online, he is approached by the most popular girl in school, Mitsuki Sanada. She brings him to her father who is a scientist studying parallel worlds. Unfortunately, Dr. Sanada's experiment sends Kazuki and Mitsuki to an alternate reality where he was never born, in which he finds parallel counterparts to people from his world. While trying to find his way, he comes across a battle between two robots, exactly like in his visions. When he accidentaly gets into the cockpit of one of the robots, it's quickly discoverd that he possesses incredible skill. He is quickly taken into custody by a group called the EDF (Earth Defence Force) and becomes the new Core Robot pilot for the robot he knows as "Hartzenen." He quickly attracts many young women to him, including Yayoi Schwael, the original pilot of Hartzenen who Kazuki rescued after she was injured and could no longer pilot it. He also attracts D, a young girl from another world who was found with the alien artifact from which the robots originated. D's astral self was placed into the body of a bioroid and acted as mechanical as the robot she pilots until she met Kazuki and began to act more human.
Kazuki moves into Dr. Sanada's house with Mitsuki, Yayoi, and D. Mitsuki often gives Kazuki a hard time, masking her true feelings for him.He is later captured by the enemy of the EDF known as the Rara Army and falls for its poster girl "Ms. Ra," who is actually Mitsuki Rara, daughter of Hiroshi Rara, the Army's leader, and is this world's counterpart to Mitsuki Sanada. This Mitsuki is sweet, demure, and less aggressive than the other and falls in love with Kazuki, eventually helping him to escape and defects from the Rara Army and joins him and the other girls in the house shortly after. Though not long afterwards "Himiko," an incomplete robot made from the artifact is sent to attack the EDF. During the attack, Kazuki is badly hurt and the original Core Robot, Zinv, is awakend. With Zinv's help, Kazuki is able to destroy the incomplete Himiko and repel the Rara forces.
Unfortunately, a new type of robot made from the artifact is deployed that can cause objects and people to be shifted between the alternate worlds. During the battle against it, Kazuki and Mitsuki Sanada are sent back to their original world. As it turns out, the frequent travel between worlds is taking a toll on the universe itself as the barriers separating them begin to break down, which will eventually lead to both worlds vanishing. Kazuki convinces Mitsuki to go back to the parallel world to help their friends win the war. However, a decision had to be made: since Kazuki and the alien technology are exclusive to each world, one must be eliminated to halt the destruction of the universes. Obviously, the choice is made to destroy Zinv who turned out to be Kazuki's parallel world counterpart.When Zinv is destroyed, Kazuki's desire for the group to stay together results in the creation of a third world, where elements from both parallel universes are combined. Kazuki's parents went abroad and left him to stay with his "Uncle" Ken Sanada, allowing him to live with all of his friends.
It's later discoverd that while it's destruction did stablize reality, Zinv was able to survive. It managed to regenerate at the bottom of the ocean. Once it was completely revived, it went looking for Kazuki. When it found him, it was decided that Kazuki and the girls would use an enthusiastic Zinv as a means for exploring space.
- The GXP novels eventually reveal that the story of Dual happened millions of years before the events of the OVAs, or even the True Tenchi Novels.
- Kazuki's adventures in space would eventually help create an interstellar civilization.
- Kazuki eventually reincarnated into Seina Yamada, protagonist of Tenchi GXP.