Under the Oak Tree (Web Novel KR) - Chapter 245

Her – a glutton without troubles or worries who crossed over and became a young fat chick with a deep vengefulness.

Betrayed. Alone. Forced to survive the deadliest dungeon in the universe. As a Tulland dreamed of adventure. To be someone who sees every-place, goes every-where, and does every-thing. All he wanted was to go beyond the confines of his tiny island. So, when the Church denied him a class, he turned to the only other being that could grant him his wish; The System. And the System delivered. Tulland got Class, but not one he ever wished for. Awakening as a Farmer, he finds himself in the one place where he can grow away from the clutches of the Church — The Infinite; a dungeon whose end even heroes of old have never seen. Armed with what dregs of power the System deigned to give him, Tulland will have to figure out how to survive, and cultivate, the universe’s deadliest dungeon. Expect: + Progression fantasy with actual farming! + A very stubborn MC + Combat! Action! Plants!

Lucille was a top student when she suddenly passed away due to a car accident she was transmigrated to the novel that she was reading before her tragic ends, and what's worse she was transmigrated in the body of the Villainess Acantha Solaris who will also die without receiving any love from everyone.

Xia Zhijun got the title ‘study god’ after scoring first place in the whole city. He’s the model of a good student in a teacher’s eyes: good grades, good manners, and quiet. When he wasn’t smiling, his entire body emits a cold abstinence aura. The girls only have the guts to look from afar and not get close.
Later, it was rumored throughout the entire school that even the study god would fight and hit on girls. Whoever dared to provoke his girl, he would teach you how to be a person at every minute. The night of the graduation ceremony someone saw him blocking Gu Siyi in the corner. He didn’t stop kissing even when she cried. He bit her lips and said in a raspy voice, “I’m going crazy…”
During college finals, Gu Siyi almost bursted out crying, “I’m such a failure. I won’t be able to find a good job in the future…And if I can’t find a good job, I can’t provide for myself…”
Xia Zhijun played with her pink earlobe and remarked, “I’ll take care of you.”
After they graduated, Xia Zhijun created a research company and Gu Siyi became the boss’s wife.
The commercial rocket, “Star of Siyi” was successfully launched. So everyone knew that the new technology superstar, Xia Zhijun has a wife who he spoils a lot.

- Description from Novelupdates