Dual! Parallel Trouble Adventure
The title refers to the fact that the story takes place in two parallel universes, a concept loosely based on multiverse theory. Plot. 22 years ago, a huge alien artifact is found on a construction site by a worker named Yotsuga. The foreman orders that the artifact be broken apart to avoid delays. As Yotsuga walks towards the dumpsters to dispose of a small piece of the artifact, the world splits into two. In one world, Yotsuga tosses away the piece and the artifact is destroyed. In the other world, Yotsuga keeps the artifact, leading to  the discovery of extraterrestrial technology that changes history. In the present, Kazuki Yotsuga is a high school student who is shunned by other students as an otaku; his web site describes battles between giant robots that only he can see, but it is mostly as a result of him being occasionally seen by the other students reacting to their "presence". One day, the most popular girl in school, Mitsuki Sanada, approaches him to tell him that she likes his stories. This is only a ruse; she lures him to her father, Dr. Ken Sanada, who wishes to study Kazuki for  his research on parallel worlds. After being thrown into the other possible world by Dr. Sanada's device (thanks to a careless action by Mitsuki), Kazuki finds himself still in Dr. Sanada's basement, but everything is covered with cobwebs. Kazuki goes home, is distracted by a real battle between two giant robots, one white and the other black. The white robot is knocked down and an injured female figure emerges from inside. When Kazuki goes to her aid, he is trapped inside the robot and somehow manages to activate it and defeat the enemy robot. Afterwards, Kazuki reaches his  home, but his parents no longer recognize him. He is found by Mitsuki, who has followed him. Along with a military escort, she takes him to the Earth Defense Force HQ, a paramilitary operation led by this world's Dr. Sanada. After Kazuki learns of this world's situation and the attempted conquest of this world by this world's Dr. Rara (Dr. Sanada's arch-rival) who is using technology developed from the artifact, he volunteers to become a giant robot pilot. Over the course of the series, Kazuki manages to attract several very different women without even trying , and he becomes a hero. He is later taken prisoner by Dr. Rara, the father of this world's Mitsuki. Mitsuki Rara eventually defects and comes to live with Kazuki and her counterpart. Later on, 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, and they discover their world's Dr. Sanada covered up their disappearance by claiming that they had eloped. 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; this will eventually lead to both worlds vanishing. A decision must be made; since Kazuki and the alien technology are exclusive to each world, one must be eliminated to halt the destruction. The robots are destroyed, and the worlds combine into one, an expression of Kazuki's wish for all his (girl)friends to continue to stay together with him (even though the action is again caused by Mitsuki's carelessness). Masaki Kajishima, confirmed that "DUAL!" is in fact set in the  distant past of the "Tenchi Muyo!" universe. Music. Opening Theme: Ending Theme: Connections to "Tenchi Muyo!" Universe. It has been confirmed by the creator of "Tenchi Muyo!" and "Dual!" that the two series are related, and in fact occur in the same universe. A mecha, confirmed in the "Tenchi Muyo! GXP" novels to be Zinv, is found during an episode of "Tenchi Muyo! GXP" which runs parallel with the "Tenchi" OVA Series. The hero of the "GXP" series, Seina Yamada has been confirmed to be a direct reincarnation of Kazuki Yotsuga and, in a complicated way, several others are basically  partial reincarnations of the rest of the cast. In fact, "Dual"! is so consistently relevant to the "GXP" novels they can be viewed as a distant sequel. Production. Dual! was inspired by the popularity of Neon Genesis Evangelion when it aired in Japan in the 1990s with the main characters inspired by the dynamics of Shinji, Asuka, Rei and Misato. Media. Dual! was released in Japan via VHS, Laserdisc and DVD from June 25 to December 22, 1999. A Blu-Ray version was released in Japan on October 11, 2018.