OVA
Description
Tennyo Masaki is the daughter of Nobuyuki Masaki and Kiyone Masaki, making her the older sister of Tenchi Masaki and the half-sister of Kenshi Masaki. First appearing in the third OVA series, Tennyo possesses a youthful physical appearance identical to her deceased mother Kiyone, despite being chronologically 80 years old. To conceal the Masaki family's extraterrestrial heritage and slowed aging from Earth's developing civilization, she maintains an elderly disguise during public interactions. This necessity prompted her departure from Earth soon after Kiyone's death, avoiding suspicion from former classmates still residing nearby.

During Tenchi's infancy, Tennyo occasionally leveraged her identical appearance to swap places with Kiyone and care for him. She returned to Earth during OVA 3 to formally introduce Tenchi to his arranged fiancée, Noike Kamiki Jurai. Initially participating in Nobuyuki's planned ruse to impersonate Kiyone, she abandoned the charade when Tenchi became emotionally overwhelmed upon mistaking her for their mother, clarifying their sibling relationship instead. Following this reunion, she took a final trip to Hawaii with her elderly classmates using her aged disguise, accompanied by her grandmother, Airi Masaki. She later returned to attend Nobuyuki's wedding to Rea Masaki.

Professionally, Tennyo works in one of Airi's Galaxy Academy production workshops in space and holds recognition as a young Philosopher. The Tenchi Muyo! GXP novels highlight her significant contribution to designing the armaments for the original Kamidake, the first ship assigned to Seina Yamada. After Miki Steinbeck's apparent death, she comforted Seina, who also initially mistook her for Kiyone and reacted with distress. Seina views her with a blend of sisterly and maternal feelings due to her connection to Tenchi.

In OVA 4, Tennyo is shown in a romantic relationship with Hakuryo Masaki, who also grew up in Masaki Village and joined Airi's workshop. Their relationship faces complications, humorously attributed by Hakuryo to "timing" issues implying difficulty finding moments alone away from Airi's intimidating presence. By OVA 5, Tennyo actively researches her mother Kiyone's previously undisclosed investigations into dimensional travel and Rea's origins, specifically concerning Rea's mission to bear a child destined for the alternate dimension planet Geminar. During this period, she transitioned her hair color from its original black (or the grey she used while impersonating Kiyone) to white or light lavender, likely to further distinguish herself from her mother's appearance and avoid recognition by those who knew Kiyone.

Tennyo shares a unique familial rapport, being the only person permitted to address Airi as "grandmother" without inciting anger, though Airi requests she refrain from doing so. While briefly associated with piloting the mecha Yomotsuookami in OVA 5, it was clarified this was Kiriko Masaki's mecha, and Tennyo's specific role remains unspecified.