Toaru Kagaku no Railgun SS - Volume 1, Chapter 3

[Ding! Congratulations to the host for obtaining the 9-Tailed Heavenly Demon Fox Bloodline.]The Celestial Fox Deity: “Little Ancestor, our geniuses are struggling to advance their bloodlines. Could you spare just a small drop of your diluted blood?”…Cain wakes up only to find himself transmigrated into a novel that he had read a few years before his death.In this new fantasy realm where the strong are respected and the weak are trampled, Cain awakens his “Unique SSS-Ranked Primordial Beast Master Talent” before an error happens and merged with “Extra’s Harem Gacha System” which can help him become stronger by having sex with powerful women, including those summoned from the system’s Summon Pool.[Ding! You have shared an intimate moment with the Goddess of Light][Ding! You have received …% of her stats attributes][Ding! You have increased her stats attributes by …%]After merging his talent with the system, he can also contract and evolve powerful beasts, instantly upgrading their ranks using Evolution Points.With the ability to convert money into Evolution Points, Cain decides to build his own force, amass wealth, and take full advantage of the system’s potential to rise above all.[Ding! Do you want to refine the Ice Dragon’s Evolution Pill?][Ding! Do you want to refine the medicine liquid of God's rank?][Ding! Do you want to refine the Godbreaker sword of the God’s rank?]…

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

The Laughing Demon, Zǔ Zhòu, who had plunged the Nine Heavens into despair, met his demise by defying the Laws of the Dao. However, fate intervened. Transmigrated into a new body millions of years later, with his forbidden bloodline still bound to his soul, he seeks to live this new life as he did before, stopping at nothing, even if it means destroying the Heavenly Dao itself!