what she left behind

Not necessarily. Many stories that claim to be 'based on true events' still take creative liberties and might not be entirely factual. It could be inspired by real-life but with alterations for dramatic effect.

It mainly focused on the emotional journey and personal growth of the main characters.

The main theme could be abandonment. Since it's about those she left behind, it might focus on how the act of one person leaving affects others in terms of emotional distress, readjustment, and the sense of loss.

The box left behind by Ye Qingmei contained a Barrett sniper rifle, two letters, and possibly other items. The first floor was a Barrett sniper rifle. It had been split into three parts, but there were no bullets. The second layer was a letter to Wu Zhu, expressing his longing for him and hoping that he would destroy the box after reading the letter to prevent it from falling into the hands of someone with ill intentions. Other than that, there was no information about the other items in the box.

The box left behind by Ye Qingmei contained a sniper rifle, two letters, and possibly other items. On the first floor was a Barrett sniper rifle. It was split into three parts, but there were no bullets. The second layer was a letter to Wu Zhu, expressing her longing for him and hoping that he would destroy the box after reading the letter, lest…

The box left behind by Ye Qingmei contained a Barrett sniper rifle, two letters, and possibly other items. On the first floor was a Barrett sniper rifle. It was split into three parts, but there were no bullets. The second layer was a letter to Wu Zhu, expressing her longing for him and hoping that he would destroy the box after reading the letter, lest…

The box left behind by Ye Qingmei contained a sniper rifle, two letters, and possibly other items. On the first floor was a Barrett sniper rifle. It was split into three parts, but there were no bullets. The second layer was a letter to Wu Zhu, expressing her longing for him and hoping that he would destroy the box after reading the letter, lest…

The box Ye Qingmei left behind contained a Barrett sniper rifle, two letters, and possibly other items. On the first floor was a Barrett sniper rifle. It was split into three parts, but there were no bullets. The second layer was a letter to Wu Zhu, expressing her longing for him and hoping that he would destroy the box after reading the letter to avoid revealing the secret. As for the other items, the specific contents were not mentioned.

The secret Ye Qingmei left behind was the forbidden door at the bottom of Taiping Courtyard's lake. This door was thought to be the final location of all secrets. According to the documents provided, Ye Qingmei mentioned in her letter that this door was forbidden to be opened because opening it might subvert the order. The Forbidden Door was related to Fan Xian and his arrival in this world. The box left behind by Ye Qingmei was the location that the Overwatch Council had been searching for. Inside the box was a heavy sniper rifle (or a crossbow, modified in the TV series), two letters, and items that might be abortion medicine. Ye Qingmei had set a password for the box that could only be unlocked with the five-stroke input method. One of the letters was for Wu Zhu, while the other two were for the Qing Emperor and Fan Xian. Ye Qingmei's origin was a mystery. She was a modern person who had possessed modern thinking and technology after transmigrating to this world. She used to be a special forces soldier and stole a heavy sniper rifle when she transmigrated. The box Ye Qingmei had left behind aroused the curiosity and effort of Fan Xian and the others. In the end, Fan Xian opened the box with the key and discovered Ye Qingmei's secret.

The secret that Ye Qingmei left behind was related to the forbidden door at the bottom of Taiping Courtyard's lake. This door was thought to be the final location of all secrets. It was related to Fan Xian's origins and his existence in this world. The specific secret details needed to be read in the original novel, Chapter 121 of Celebrating Years. The Forbidden Door was related to Ye Qingmei's research and the nurturing of people at the Great Grandmaster level, including the Qing Emperor and Ye Liuyun. Ye Qingmei also left behind a Barrett sniper rifle. This sniper rifle had powerful destructive power. She had once used it to kill the Qing Emperor's two brothers and help the Qing Emperor ascend to the throne. In addition, Ye Qingmei also left a portrait, showing her image of worrying about the country and the people by the Yellow River. As for the contents and material of the box Ye Qingmei had left behind, as well as the reason why the world had no rules in her letter to Fan Xian, there was no relevant information at the moment.