Su Yi, a modern social animal, traveled through time and became a small official in the household department of the Tang Dynasty, and discovered that the account book was actually a secret book, which could fine-tune the national destiny by modifying the numbers. He used Excel-style accounting to "optimize" taxes, but accidentally caused the Xuanwumen mutiny to break out three years in advance. He was even mistaken by Li Shimin for being a hermit expert who could predict the future.
