MTL - The World That Tao Rules - Chapter 11 Flashy

Xia Yan passed through to the world of Bleach and became an eleven-year-old boy. He was rescued by Renji and Rukia in the Seireitei, and he was studying at Shin’ō Academy, and he was a student of the same class.
He is a top student of the Shin’ō Academy, and he is vying for strength by various teams. In the end, he has entered the first team of secret mobile maneuvers.
He will use punishment to kill every person who tries to threaten the martyrdom and protect his loved one.

- Description from Novelupdates

Others treated disease to save person, he treated disease to steal heart.

The Frost Goddess was deeply captivated by him. The gentle and kind beautiful teacher was completely enchanted by him. Even the cold and beautiful female assassin melted quietly because of him.

Competing in medical skills? He was the one who treated the Godly Doctor. Competing with backgrounds? Leaders rushed to him. What? You actually wanted to compete with him in a match for match? Looking at the gentle girl beside him, Tang Yu had a headache as he said, “Beautiful girl, how did you fall in love with me?”

- Description from Novelupdates

She, Xue Fanxin, a famous medical genius in the 21st century, had transmigrated into the body of the dumb daughter of the Grand Duke.

This is a prequel to the anime movie To Aru Majutsu no Kinsho Mokuroku – Endymion no Kiseki.

Just before the completion of the Academy City space elevator “Endymion”, the main characters Kamijou Touma and Index encounter a level 0 girl named Arisa. The Magicians are after Arisa, and they attack Academy City. A female leader named Shattoaura leads a unit from Academy City against the attack. Kamijou and Index learn from Stiyl that Arisa is key to a brewing war between the sides of Magic and Science. When science and magic cross paths, the story begins with Endymion as its stage!