The Sun in the Dark Episode 13

Bai Yi Xi learned that she possessed the power of the Night God within her. Wan Gu Chen told her that only the Sword Bearer could eliminate the Night God without harming her. The two traveled far and wide in search of renowned doctors, attempting to suppress the power of the Night God. Bai Yi Xi often playfully teased Wan Gu Chen, and their relationship grew increasingly close. However, the power of the Night God within Bai Yi Xi gradually spiraled out of control, causing her to feel unwell and restless. When Wan Gu Chen returned and found her unconscious, he was frantic with worry. Bai Yi Xi prepared a gift for Wan Gu Chen, hoping that after her passing, he would be able to let go of his grief. Hua Yu Ying informed Bai Yi Xi that the Night Clan possessed a potion that could cure her. Though Bai Yi Xi had her doubts, she decided to go anyway. Wan Gu Chen was deeply wary of Hua Yu Ying, but his magical powers had been weakened, leaving him unable to stop her. Bai Yi Xi returned to the Night Clan and was forced to become the Night God. When Wan Gu Chen awoke and discovered she was missing, he rushed back to the Night Clan. (Source: Chinese = zuiai.tv || Translation = Deepl)