Woman Reborn as a Man: Born into an Interstellar Matriarchal Empire?!

A female ghost transmigrates into the womb of a woman in an interstellar matriarchal empire.

The good news: her mother is the empress!

The bad news: the female ghost has become the empress's youngest son... son... son...

[No romance] [But there is family love and friendship]

[Heads-up] The story starts when the protagonist is still a fetus and develops gradually. This is not a wish-fulfillment story; it gives a detailed introduction to the world, and the pacing is not fast.