That time i got Reincarnated as A Dragon - Chapter 20: Formation of a new organization

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

In a world fractured by conflict and haunted by shadows of the past, Kokushibo—the first Upper Moon demon—meets his end, only to awaken in a new life. Reincarnated as Crimson, a child born into a different family, he carries the memories of a past he cannot escape. Burdened by centuries of guilt yet indifferent to the present, he resigns himself to duty—until an unexpected bond with his newfound family begins to thaw his hardened heart. As he struggles between the weight of his past and the weight of the new life, Crimson must decide whether he will remain shackled to his former sins or embrace the possibility of peace.

After a car accident, a modern loving couple, Zhou Ying and Gu Chengrui, both transmigrated through space.

Zhou Ying became a jinx everyone despised and had difficulty getting a full meal.

Gu Chengrui became the son of a wealthy, cold, and violent family.

They hated him and were indifferent to his wife. With no one to love or care for the couple, they made a decision.

They decided to split up from the family!

They were penniless in their new house, which had nothing. But there’s nothing to be afraid of!

They had their interspace and wisdom to get rid of poverty and get rich in minutes! As the days started getting better, trouble came knocking on their door.

The family wanted them to go back to being their mule?

No way! The couple stood united and called them out on it, refusing to go back!

Their old rival, a father-daughter pair, wanted to steal their house?

The couple rolled up their sleeves and clashed with them head-on! After much difficulty, they finally had peace, but then a disaster that happens once every thousand years came…

The formless ancient world was infested with despicable demons. They hunted and feasted on mankind, keeping the human civilization constantly in a weak and suppressed state.

During the first known year, a magical mountain descended into the world from the realm of the Gods. Carved on this enormous mountain was a message: ‘Heaven Prevails’…

After the Grand Descent, a name that was given to the descending of the mountain, the Three Great Sages made their ways to Mystic Mountain where they learned to harvest what we now call magic, establishing the Mystic Cults and eighty-one sacred shrines to help aid mankind with the cult’s mystic powers against the eternal fight to the death with demons.

- Description from Novelupdates