After Five Years of Amnesia, I Became a Master

Seventeen years after transmigrating to the Liang Dynasty, Lu Wujiu studied both civil and martial arts, but only knew a little of each. He thought he could live a peaceful life, but while traveling south with his father to take up a post, they encountered a demon. When he woke again, five years had passed in the world. A storm on a desolate mountain, a tomb-robbing camp, a Daoist nailed by his weapon, and a sword named Zhaoye pulled from a spirit-sealing coffin. Lu Wujiu has lost five whole years of memories, yet inexplicably possesses formidable martial arts. His father is missing, and his only companion is a gluttonous red-tailed spirit marten. To recover the lost five years, he enters Linjiang City, but inadvertently gets involved in a demon bandit case and is arrested as a murderer by former acquaintances. Worse, a woman seems to be hidden within the Zhaoye sword. — Description from novelcodex.org