Kadafuu Raiden

From Friendship Scans:

The setting: China during the period of the Three Kingdoms!
The man: Hua Tuo, the great doctor who has alighted to earth, curing all illnesses, performing exorcisms and even exterminating all manner of monsters with ease...when no one else can!

But after every success, why is he dragged away from the celebratory feasts and beautiful women? And who would have the gall—not to mention the power over him—to send him off on an unending journey in (sort of) poverty and (relative) discomfort?

When grateful people try to press monetary payment (or women) upon him, he (well, his twin companions who step in and speak as one) refuses all, but asks them to always recite the prayer, “Namu Amidahba.”

What could the true goal of Hua Tuo be as he travels with the mysterious twins, the brother and sister Ri Yao and Yue Jing, who are constantly trying to keep him in check?

What great sin could he possibly have done to be forced to live a life so far beneath his merits?