He slept with his sister's best friend, who turned out to be a top-tier succubus school beauty.

[Slice-of-life romance + Single female lead + Succubus school beauty + Experienced senior + Senior with thunderous quotes]
Lu Jinyu wakes up from a hangover
Lying in her arms was her sister's best friend, Nangong You, the number one goddess of Jiangda University.
This unattainable beauty, so high and mighty, was now curled up in his arms, sleeping soundly.
One night of absurdity caused their relationship to completely spiral out of control.
From then on, the succubus school beauty flirted with him, pampered him, protected him, and showed him boundless favoritism.
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Roommate: "Damn, didn't you say you were broke? Who bought you this computer?"
Lu Jinyu: "Senior Nangong."
Roommate: "Keep bragging! Keep bragging!"
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Roommate: "Who did you go out to eat with?"
Lu Jinyu: "Senior Nangong."
Roommate: "Keep bragging! Keep bragging!"
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Roommate: "Holy crap, you're dating someone? With whom?"
Lu Jinyu: "Senior Nangong."
Roommate: "Keep bragging! Keep bragging!"
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Unbeknownst to everyone, Lu Jinyu had already begun a sweet romance with the school beauty...