MTL - The Other Shore of the Immortal Firmament - Chapter 999 Top 10

She was a famous assassin who had killed important figures, but ironically, she was killed by her own lover.And when she thought she was dead, it turned out she was occupying the soul of a young girl who was tricked by her own family.'Because I have been reborn, I will take revenge on the people who planned my murder and also teach a lesson to the people who underestimated the girl whose soul I reside in!'However, things become complicated when she has to marry a cold man, whom she spent the night with.

Zhuang Feng is in his last year of high school, and he’s just moved to the city. He lives with his good-for-nothing cousin, who’s always on business trips falling for get-rich-quick scams, and his Saozi (sister-in-law), who tries to make his life miserable as much as possible. There’s one upside, though; she. is. freaking. hot. But one day, he found a piece of her underwear in the bathroom…. And unfolded a series of events that will turn his life upside down.

- Description from Novelupdates

Entering Tokyo in the bubble era, in this strange era, the only familiar ones are Matsuda Seiko, Nakamori Akina, Kudo Shizuka…

- Description from novelbuddy

When a person dies, they either die light as a feather (aka unimportant) or heavy as Mt. Tai (aka very important).