When Kanzaki Rin was seven, her parents brought home a beautiful stone and gave it to her.
She loved it so much that she even kept it beside her while she slept. Over time, the stone somehow fused with her body.
Young Kanzaki Rin couldn't tell whether the stone had really fused with her or if she had simply lost it, so she kept the matter to herself.
She never imagined that the beautiful stone was the legendary Sessho-seki.
The 11th District government's operation to capture Tamamo-no-Mae had actually been orchestrated by the Nest of Life. Their goal was to obtain the Sessho-seki, which was said to hold the power to grant eternal life.
But after capturing Tamamo-no-Mae, they discovered that she didn't have the Sessho-seki.
Somehow, the stone had ended up in Kanzaki Rin's parents' hands before fusing with her body.
Eleven years later, the Sessho-seki finally awakened inside Kanzaki Rin, giving her a body that produced its own poison.
The Nest of Life had been investigating the Sessho-seki's whereabouts all along, and Kanzaki Rin's unusual condition quickly drew their attention.
Although Kamikawa Takumi was already one of the Aces at the time, the higher-ups saw him as little more than a hired fighter.
And eternal life was every ruling class's dream, so no one interfered with the Nest of Life's abduction of Kanzaki Rin.
They thought they'd covered their tracks perfectly, but they hadn't realized that Kamikawa Takumi had secretly marked his sister to ensure her safety.
Kamikawa Takumi rushed back and stormed the Nest of Life to rescue his sister. He tried to kill Fujiwara Hirotetsu, but failed.
Two other Aces arrived to stop him, and the two sides fought a major battle in Tokyo. Gravely wounded, Kamikawa Takumi fled the 11th District with his sister.
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