While the Beast's origins are unknown, what is known is that it revealed itself to Satsuki Yatouji, destined to be a Dragon of Earth, when she was five years old. The Beast introduced itself to her in cyberspace, where it helped arrange for the death of her father in a traffic accident, and later her escape from a scientific research facility. The two remained inseparable ever since.
The Beast and Satsuki have a unique symbiosis, due to Satsuki's unique ability to interface with it via computer cables inserted beneath her flesh. However, the Beast is not her servant; it possesses a form of consciousness, and over the years, developed feelings for Satsuki that resemble love. The Beast maintained a relationship with Satsuki that could be interpreted as courtship; it is surmised that that is why it fulfills her most ruthless whims, like the death of her father or the assassination of the scientists holding her prisoner after his death.
Once Satsuki joined the Dragons of Earth and was introduced to the Beast personally, they shared a key role within the organization: namely, to serve as both their main technological interface, and their primary weapon against modern technology. Kanoe referred to the Beast and Satsuki as each other's "pet ".
Satsuki and the Beast became two of the Dragons of Earth's most effective, ruthless operatives. Kanoe, the Dragons of Earth's "employer", once requested data on the Imperial Household Agency and the Ministry of Research Cameras. To remove the protection programs surrounding this data, Satsuki and the Beast caused a blackout througjout the area Tokyo where the information was held, erasing the data of the National bank computer and completely cutting all phone lines.
The Beast has the ability to compute probabilities of success or failure of any given operation as needed, and possesses some offensive powers within the physical world; it can turn electrical cables into mechanical tentacles that are powerful enough to destroy physical objects and harm living beings, including spirits (as evidenced when Yuzuriha Nekoi's guardian spirit, Inuki, sacrificed himself to protect her in battle with Satsuki and the Beast).Beast's rudimentary feelings of love and possessiveness towards Satsuki began warping into jealousy when Yuto Kigai started to invest more time with her on a social basis. These feelings came to a head during a battle between Yuto and two Dragons of Heaven, Seichirou Aoki and Karen Kasumi. After Karen gained the upper hand in the fight, Satsuki tried to force the Beast to save Yuto. Beast reluctantly acquiesced once, but when it was clear that Yuto would not survive the fight without further aid, Beast refused to aid a second time despite Satsuki's desperate pleas, and when she attempted to disengage from it, Beast trapped her with an ever-increasing number of interface cables, eventually imprisoning and killing her within it. However, as Satsuki was the only person who could interface with and operate the Beast, this also effectively served as the Beast killing itself.