For Tenchi Masaki official cannon head to Tenchi Masaki OVA
In the first TV series, Tenchi Universe, Tenchi is similar in personality to the Tenchi of the official canon but is not as powerful as his counterpart. His abilities seem to not go beyond his use of Tenchi-ken (Sword Tenchi) and the power possessed by members of Jurai's Royal Family. Sword Tenchi is just a weapon and is not revealed to be a Master Key. Tenchi attends school in the city, but it is a long commute for him because he lives in the mountains of Okayama near his family's shrine with his widowed father, Nobuyuki, and his grandfather, Shinto priest Katsuhito.
Tenchi once again leads an ordinary life until the arrival of Ryoko to his home. Ryoko claims to be being chased by a vicious space pirate who actually turns out to be Galaxy Police detective Mihoshi. After the ordeal, both alien girls are stuck at Tenchi's home without any complaints from Ryoko who falls head over heels for Tenchi.
After the arrival of Ryoko and Mihoshi, Planet Jurai's Princess Ayeka arrives on Earth after receiving a distress call from Mihoshi. Tenchi gets stuck in the middle of lifelong rivals, Ryoko and Ayeka's constant bickering and excessive fighting only enhanced when Ayeka falls in love with Tenchi. Tenchi graciously welcomes the princess into his home after her spaceship crashes. He does the same for her younger sister Sasami who becomes like a little sibling to Tenchi. After Sasami comes to mad scientist Washu who the gang accidentally releases from the Masaki Shrine after 700 years of being imprisoned there by the Galaxy Academy for creating weapons of mass destruction. Completing the extended Masaki family is Galaxy Police detective Kiyone Makibi, Mihoshi's partner who reluctantly comes looking for her ditzy comrade.
Tenchi's life becomes adventurous and chaotic, which in fact, is the main theme of the series as life is supposed to be a carnival and though the life can be a bit off-putting, Tenchi is firmly content with it despite the trouble that the girls may cause. Unfortunately, the carnival turns disastrous when Tenchi and his extended family become fugitives in space on the run from the Galaxy Police and the Army of Jurai who are dead set on capturing Princess Ayeka and Sasami for "treason" and Ryoko for her crimes as a space pirate. Tenchi travels with the girls across the universe in order to reach Jurai to find out exactly what is going on. After many adventures through space, Tenchi and the gang finally reach Jurai where the truth about Tenchi's lineage is revealed; his grandfather is actually Yosho, the Crown Prince of Jurai, which makes Tenchi heir to the throne. Tenchi bravely goes up against Kagato, who has been impersonating Yosho in order to take hold of the throne.
Like in the official canon, it would seem that Tenchi has some special power that other Juraians don't seem to have. Before going up against Kagato, Washu tells him that from the moment she met him, she sensed that his power was far greater than his grandfather's. During his duel with Kagato, Planet Jurai chooses Tenchi as its true master.After defeating Kagato, Tenchi chooses to turn down the Jurai throne and head back to Earth, after realizing that like his grandfather before him, he wants to live a simple life without much responsibility. However, Tenchi becomes bored with living on Earth again without the girls around but is surprised when they return and Ryoko reminds Tenchi that although a carnival would eventually leave, it would always come back again.
Tenchi Muyo! In Love
After being defeated by the Jurai Emperor and the Galaxy Police centuries ago, the monstrously powerful Super A-1 class criminal Kain was imprisoned in the subspace room of the GP's headquarters, never to be released. In the present (established to be 1996, the year of the film's release), Kain escapes his bonds, destroys the GP space station, and travels back in time to take his revenge on Jurai's royal family.
The Masaki house, the shrine, and Tenchi himself all begin to fade out of existence. Washu theorizes that someone is tampering with the established timeline, and uses a shield to keep Tenchi from vanishing. The shield is only a temporary solution, so Washu sends the rest of the group back to 1970 to prevent Kain from killing Tenchi's mother Achika Masaki. Tenchi's friends assume roles at Tenchi's father Nobuyuki and Achika's high school, while Tenchi himself stays hidden to prevent causing a paradox.
After determining the exact time that Kain strikes in 1970, Tenchi tries his absolute best to defend Achika, only to see the villain escape into subspace with both his parents. Tenchi, Ayeka, and Ryoko follow and challenge Kain, but even with their powers boosted by Washu, they are no match for him. Washu sends a powerful "dimensional cannon" from the present, and Kiyone mans the weapon to destroy Kain. Tenchi is wounded, and Achika unlocks her latent Jurai power to fuel Tenchi-ken and deal a crippling blow to Kain. The group barely escapes in time before the dimensional cannon is fired into their pocket of subspace, finally destroying Kain.
Before her memory is wiped along with Nobuyuki's, Achika asks Ryoko and Ayeka to take care of Tenchi, since she will not be there for him in their present.Haruna. With no memory of his real life or any of the girls, Tenchi, an art student, takes to drawing rough sketches of Ryoko who he vaguely remembers. It turns out that Haruna was once the fiancee of Tenchi's grandfather, Yosho, who died while on their way to Earth after abandoning Jurai. Being buried in the forest, right at the tree where Tenchi disappeared, Haruna takes Tenchi into a parallel world of her creation where she can live out the life with him that she never got to have with Yosho. Ryoko and Ayeka are able to break into the parallel world and snap Tenchi out of it. Tenchi painfully leaves Haruna to go back to his world, taking with him his gift/hobby of artistry as it reminds him of a part of him lying deep inside.
In contrast to the official continuity where Tenchi does not show any of the girls special attention, it is obvious that Ryoko holds a special place in Tenchi's heart though this isn't verbally stated during the series. This is hinted at during their various intimate conversations throughout the series and the fact that in Tenchi Forever!, even with his memory gone, Tenchi constantly draws rough sketches of Ryoko only.
In the manga companion to the second movie, Tenchi Muyo! in Love 2: Eternal Memory, after leaving Haruna's world, Tenchi informs Sasami that he knows that one day he will have to choose between the girls, but he does not want to make the decision right now because he enjoys the present too much. The manga also heavily implies that Izumi, a girl that helped Sasami on Jurai during her quest to help Tenchi, is his and Sasami's future daughter. However, Sasami's narration reveals that this is one of many possible futures as, with every choice they make, they can change their destiny.