Master, Why Are You Still Crying After the Soul Exchange?

Looking for a Cultivation Novel Where the Male and Female Leads Swap Souls. The Female Lead’s Surname Is Luo, and There’s a Tianyuan Sword

I'm looking for a xianxia novel where the male and female leads switch souls. The heroine has a sword called Tianyuan, with a jade pendant hanging from it. Her surname is Luo, and she has a senior sister who later turns out to have a sea-demon constitution. Whenever she appears, rain falls. I forgot the title. Fellow cultivators, please help me find it.