Toaru Majutsu no Index: New Testament - Volume 2, Epilogue: A Rest, but a Mixture in the Dark Side. Birdway’s_Speech.

Su Ci was forced to marry the dying Second Master Shen, and the entire S City awaited her tragic fate. However, half a year later, Su Ci cured Second Master Shen and was adored by the Shen family. She is a personal disciple of a miraculous doctor, a top hacker, a racer, and the founder of a globally popular cosmeceutical brand. International conglomerate CEO Xiao Yizhou, genius director Lu Mingchen, and e-sports god anti all declared: “Su Ci is our dearest junior sister!”The man, rumored to be cold and violent, cornered Su Ci against the wall, gritting his teeth: “How many more identities do I not know about?” Su Ci smiled warmly and kissed the man's lips, “Just one last one, Mrs. Shen.”

He was promised a world of magic, dragons, and swords.What he got was a hijacked system, and a realm ruled by cultivators who crush mountains with a punch.

Gu Changge, a noble lady from a wealthy family, is a well-known business legend in Yuncheng, going into business at 15, taking over as President of Gu Group at 18 and becoming Chairman of the family business at 30.
She is murdered by her husband Shao Tianze, just to give his mistress Gu Changle a healthy heart. But a premeditated car accident makes Gu Changge revive in a new guise and settle into an 18-year-old girl, Song Yunxuan.
The new face, young body and experienced soul become her weapons of revenge. In her struggle with the four big families in Yuncheng, can Gu Changge shrink back? Will she open her broken heart again? Can she always head off dangers in power struggles?
Let’s find out if Gu Changge can revenge herself and create glory again.

- Description from Novelupdates

A martial art expert from the Song dynasty lives like a Phoenix that can live again in another body after death. This time, he happened to take over the body of a Japanese high schooler who is also a victim of bullying and has a bit complicated family circumstances.