Master, Please Give My Senior Brother Back to Me

After his master disappeared for many years, Lu Zhao took on a disciple in his place, only to discover that his new junior sister...

They actually came for their own beautiful master?

The junior sister admires the master, and the master cherishes the junior sister?

No, what about me?

Oh, I'll just dig with a shovel... no, I'll just join in!

-——

"Master never liked Junior Sister in the first place, how could he have fallen for her after meeting me? As for the rumors about her, they are utter nonsense."

In the year 9527 of the Yuanqi era, when faced with his junior sister's questioning, Lu Zhao righteously declared,

"My master is pure, virtuous, and kind; my senior brother is devoted to the sword and has no interest in women; my master simply teaches me swordsmanship day and night."

We are completely innocent! How could we possibly have any romantic feelings for each other?

...

In the year 9528 of the Yuanqi era, Song Qingruo, a junior sister from Xuanmiao Peak, ascended to the position of Empress of the Demonic Path and declared that she would not marry anyone but her senior brother, Lu Zhao.

At that time, Lu Zhaozheng and his beautiful master Yu Shuyao were enjoying their wedding night together.

Based on the above reading comprehension passages, identify the war criminal who caused Song Qingruo to become the Demon Empress, and explain why it was Lu Zhao. (250 points)

—Excerpt from "Collection of Classic Examination Questions for the Tianyanmen Unified Examination, Volume One"

[Fantasy slice-of-life, multiple female leads, love triangle, lighthearted, sweet without angst] This book is also known as "Senior Brother, What Are You and Master Doing Behind My Back?"