This business isn't entirely undoable. The Kuroda Family's assets are certainly under strict audit by the tax bureau, and can't be transferred out at all. But using the Rebirth accounts for internal gifts is still possible. Although gift taxes must be paid heavily, they won't exceed 50 percent at most, and a tenfold profit is certainly worth earning.
Considering just the Panama metropolitan area alone, so many monsters can be captured, and when the Kuroda Expeditionary Force sweeps across the Americas in the future, won't they just collect keys in bunches?
The only problem here is that Li Pan hasn't opened his own Rebirth account yet...
Well, since Li Pan doesn't really see a day when he would need any reincarnation services, why waste money on something ridiculous like that.
