On a certain day of a certain year, a certain month, the boss of the Giangaro family, Lan Yixi, received a request from Vongola IX to help her assist Li Baoen, the son of Rainbow, to train Sawada Tsunayoshi, the candidate for the tenth generation of Vongola. Lan Yixi, who wanted to refuse, was stumped by Li Baoen's question. In order to find the answer to this question, Lan Yixi agreed to go to Japan. Then her life began to change little by little. But she didn't know that a well-planned conspiracy was slowly approaching...