MTL - Lord of the Mysteries - ~ End of the testimony (below)

Tragically killed in a cruel world, Rey awakens in the body of a young noble named Theo Von Caerstellar—in a foreign land on the brink of chaos.Gifted with extraordinary intelligence, Theo vows to protect his family and exact revenge on the treacherous nobility. This marks the beginning of a brilliant young lord’s journey—one that will shake the very foundations of aristocracy!

This is a rebirth story of a normal girl, Kylie. She was a normal girl, living a normal life. Married and had kids. Nothing outstanding about her, but nothing terrible either. Then she was attacked and left to die.

Her soul screamed in pain at having to leave behind two small children that needed her, yet she couldn't do anything. As she entered eternal darkness ... it took her some time to realise that she was not dead. She was alive, only yet to be born.

And she was a boy.

This is the story of a person who transmigrated into a world with a radically different worldview.

So different, in fact, that he is considered a female in that world!

Cheng Nuo: What? Why did you say that I’m female?

Author: You only have one Tintin. The males of this world have two Tintins.

Cheng Nuo: No way! My hands are itchy… I want to cut one off!

- Description from Novelupdates

Kyo Mazuru traveled to the world of Bleach and landed in the forest of Menos Grande at the beginning.Picking up a asauchi left over from Shinigami's death, and starting with a sword, he spent hundred years in the forest of Menos Grande to survive, slashing countless hollows, and his slashing skills reached the peak, until one day, he met a man who claimed to be Mr. Aizen Sōsuke!Mr. Aizen couldn't bear him to live alone in Hueco Mundo, so he invited him out of there and brought him to Soul Society!After that, Kyo Mazuru's Shinigami career began!