Baka to Test to Shoukanjuu‎ - Volume 2, The Fourth Question

In the age of Mecha for everyone, people could travel to the Endless Abyss to gather materials, enhance and forge their own Mechas, and thus wield the power to destroy heavens and earth.Jiang Chen had transmigrated and awakened the talent [Undying Barehand]. Once his Mecha shattered, he could permanently absorb its power and attain a multiple enhancement.…At the bottom of the abyss, the ancient demon god exerted great effort and finally broke the titan Mecha, but from the shards extended a hand that held down its head.“Congratulations, you’ve unlocked my restraints.”

In her previous life, An Xiulan had been oppressed and tortured by the members of Duke An's household. Her legitimate status wasn't enough to save her from the schemes of jealous siblings. For sixteen years, she tolerated the oppression inflicted on her but in the seventeenth year, she was pushed to death into the frozen lake.

Now she has reincarnated into the body of a youthful girl in the modern world who died in a car accident. She was given everything she was devoid of in her last life– family, love and education.

Graced with a new life, An Xiulan is determined to strive towards a better life. She will be the best daughter. She will study hard. And she will stay away from puppy love.

Nothing must come between her path to become a top scholar!

But there seems to be a hitch in the plan.

Why was the backbencher Han Zixin following her to the library, laboratory, playground and even the principal's office?

Wasn't Big Boss Han allergic to studies?

Why was he following the campus Belle?

…

Teacher: An Xiulan is a top student. We must preserve her at all costs.

Class Ten gulped as they recalled how a certain bro-con had supplied cheating slips to his model student sister in monthly tests subsequently resulting in her topping the exams!

Lu Xuan: No one is allowed to bully my sister!! Only I can bully her!

Everyone in class Ten: ????

A few days later, class Ten witnessed the delicate looking youthful girl chasing her self proclaimed brother with a hockey stick!

The delicate looking campus Belle wasn't delicate at all!

...

A delicate girl can't possibly make two big gangsters of Jingyuan Highschool dance on her tunes?

At some point in the 21st century, the Christian God stopped listening to the prayers of humanity. Monsters with colossal strength and endurance began to emerge and humanity entered its darkest period.

On the distant Tianxiu Planet, there exists a group of unusual and intelligent beings. They consist of neither children nor elders. They have neither birth nor real death. They are born into the world through an extremely special process and have managed to keep their fundamental memories of survival through their endless reincarnations.

They are the Tianxiu people.

For every Tianxiu person, if they find someone they like and want to bind as partners with each other — then they would have to go through a life or death Adult Ceremony. The winner of the ceremony will become the absolute dominant in this spousal relationship.

While the defeated one will be referred to as — Qizi.

- Description from Novelupdates