The Chemical Atlas
Human Yakuza Social Adept, Casey-Clone
She has been encountered on the arm of Jack Frost appearing to be an elf. When knocked unconcious, she looked exactly like Just Casey. Casey was once able to telepathically connect with her for a brief moment during her initiation into the Manifold Path and was able to perceive she was in a powerful meeting of the Yakuza Shotozumi-rengo. She has also been apparently asking around about Just Casey since that encounter on the train.
Since then, it has been revealed that Tiger Hoshi is an influential member of the Shotozumi-Rengo Yakuza in Seattle. She joined the Yakuza to escape the long reach of the Wounds of Odin, who wanted to recruit her as a teenager because she is another Casey-clone, of which they boast two very dangerous members already.
There may be an uncertain relation between her moniker, which was also that of the person who brought her into the Yakuza, and the title shared by the founding CEO of Mitsuhama Computer Technologies.