Who was King Zhaoxiang of Qin's mother?
King Zhaoxiang of Qin
Because King Zhaoxiang had not yet legally come of age (traditionally at the age of 20), his mother, who was now known as Queen Dowager Xuan, became the regent. She was supported by her brothers, Wei Ran and Mi Rong (羋戎), as well as two other sons, Prince Yi (公子悝) and Prince Fu (公子巿), the four of them collectively known as the "Four Nobles" (四貴).
King Zhuangxiang of Qin
In the meantime, through rewards and machinations, Lü Buwei helped Yiren return to Qin. He also successfully conditioned Lord Anguo's primary spouse, the childless Lady Huayang, to adopt Yiren as her own son, thereby making Yiren become Lord Anguo's legitimate heir apparent. As Lady Huayang was a native of the Chu state, she renamed Yiren to "Zichu" (lit. "son of Chu"). Upon the death of King Zhaoxiang in 251 BC, Lord Anguo ascended the throne and became historically known as "King Xiaowen", but he died in the following year just three days after his coronation. Zichu succeeded his father as the king of Qin and became historically known as "King Zhuangxiang of Qin". He named Lü Buwei as his chancellor, Lady Zhao as his queen consort, and Ying Zheng as his crown prince.