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Sango (珊瑚 ,Sango?) formerly known as The Black Emperor (玄帝,Gentei?) is a companion and contracted beast of Touya on his journey. She is the half of the Genbu (玄武,Genbu?), the other half is Kokuyou and they are one of the Four Divine Beasts and also the leader of the Scaled Creature.
Sango's true appearance is a 4-meter-high tortoise. She and Kokuyou are both an union being and inextricable. After Kohaku told them about the trouble that they might cost because of their form, they then changed their appearance in similar way to the Kohaku's form.
The Genbu (玄武,Genbu?) which later known as, Sango and Kokuyou, are one of the divine beast that can manifest in the world once every few decades or centuries, unless they are being summoned by human .
Intimidation Aura: Sango and Kokuyou are able to release suppressing aura that render all individual, which have lower magic level in respect to the divine beast, becomes immobile.
Long-Ranged Telepathic Communication: Sango and Kokuyou are able to make telepathic communication with their master and among the divine beasts regardless the distance. They also able to include other people into this communication line.
Form Transformation: Sango and Kokuyou are able to change her menacing true form appearance into cute young beast form (Child Form) and back as they pleased.
Floating: When in her Child Form, she can float in the air while reducing her movement speed.
Magic Barrier: Sango and Kokuyou have magic barrier that is able to repel all type of physical attack completely and also all type of magical attack with respect of the caster magic level.
"Then, this one will also from now on call thyself [Sango] with gratitude." - Sango accepting her new name from her master, Touya.
Her name, Sango (珊瑚), is the Japanese word for Coral, symbolising her connection to water.
Their epithet, Gentei (玄帝), is composed by "gen" (玄) of Genbu and "tei" (帝) which means emperor. Literal translation of this word is "emperor of Gen", which is meaningless. However the character "gen" (玄) of Genbu can be also read as kuro (くろ kuro) which mean black. Therefore, Gentei (玄帝) is best translated as black emperor.