(No female lead, and the protagonist isn't ruthless. He's softhearted and merciful. Later, he becomes the second patriarch of Myouren Temple.)
When Wang Wu first arrived in Gensokyo, his dream was to save up enough money to buy a mansion with seven courtyards, facing north and sitting south. On the thirtieth day of the second month, he went around the Human Village begging for alms and offering blessings. He said a few kind words to the children at the Temple School and earned fifty copper coins.
On the first day of the third month, he went to the Night Sparrow Diner and had a huge meal. He spent every last copper coin. Oh, Wang Wu, Wang Wu, why can't you control yourself?
On the second day of the third month, he bought a stack of talisman paper from Nue Houjuu of Myouren Temple. The price was a bargain, and buying in bulk got an even better deal. Apparently, she'd imported it from the Hakurei Shrine Maiden for one copper coin a sheet, so I could sell each sheet for ten copper coins. Nue Houjuu really is an honest youkai.
On the third day of the third month, what do you mean, "the red murderer"?
A poem to introduce Wang Wu:
He is an inner sage and outer king, and so he is called King. Fifty is the number of the Great Expansion, and so he is named Wu. The sages of old have always shared one heart. Through reincarnation, his primordial spirit descends. He walks until the rivers run dry and the mountains and seas end. Without support or dependence, he rides the void. All things are one, wholly and truly. Creation turns the heavenly essence into a golden pill. He transcends his true nature and surpasses the Dharma body. Gaining nothing, losing nothing, he leaves the root of thought. Suddenly, he transforms consciousness and enters Gensokyo. He knows the White Lotus and roams heaven and earth. His divine light is whole, elusive and without trace. Who among the people knows my true self?
"Wang Wu, lay devotee residing at Myouren Temple, at your service!"