1st arc would be when they're high school students. The remarkable tops are Cheng Huai, Jiang Zhao and Mei Song introduced in this arc and they are 3 of the 4 main gongs or I take it as so. Cheng Huai was the one to steal the MC's v*rginity btw. MC also tried to run away in this arc but was caught by Cheng Huai and "punished".

2nd arc's timelime is when they are in college. MC became the student council's president after another student signed his name up as a candidate. In this arc, the 4th main gong was introduced, Shu Qingyu, a professor. Shu Qingyu thought MC was seducing him at first but later found out MC really is innocent after all and is easily taken advantage of even after getting violated by so many men. By violation, MC acts as if he doesn't like it but he actually does like it. Shu Qingyu gave a recommendation for MC to a professor (?) in a well-known university (?) because MC wanted an intership to be a teacher and at the end of the arc MC left the college to go for an internship after the 3 main gongs tried to stop/persuade him from leaving but they failed.

3rd Arc's timeline is when MC became a professor (?). I honestly just skimmed through it so I can't provide much info about this arc lol. Anyway at the end it was revealed MC had a s*x addiction or s*x disease after having MC check up with a doctor. The cause was excessive indulgence in s*x and the body getting used to it, making the body crave for s*x. The 4 main gongs felt heartbroken for MC because they knew it was because of them MC turned out like that.

After finishing the mission, MC was given the option whether to leave or not and he decided to stay in that world. The gongs had a dream of MC where after completing missions MC would immediately leave them behind in those worlds with no hesitation and they woke up panicked. They checked in on MC and were relieved to find he was sleeping. They thanked MC for not leaving and staying with them even though when they woke up they had no memories of their dream but they still were panicked.

For the s*x addiction MC was diagnosed with, it wasn't fully true bcs MC really had a high s*xual desire more than ordinary people has.

Just to be clear, in my opinion the MLs really did love MC at some point and in the end

Quick Transmigration: The Beauty Targeted by the Mad Critics

You can take Mad Critics as the prequel of Student Becomes Plaything although as far as I remember it wasn't explicitly shown that there is a connection of the two novels in Student Becomes Plaything. Both can be read as a stand alone though so no worries.

SPOILERS FOR THE ENDING OF MAD CRITICS BELOW

In the last chapter of Quick Transmigration: The Beauty Targeted by the Mad Critics we would see Shen Cheng talking to the MC (Yu Nanzhi) of that novel after Yu Nanzhi had finished world hopping and completing his mission for the 9 worlds. Shen Cheng showed the mission of becoming a "rag" to Yu Nanzhi asking if he wanted to take it but Yu Nanzhi said he wanted to have a vacation and Shen Cheng is more suitable for the mission. After that we have this novel, showcasing Shen Cheng taking the mission he offered to Yu Nanzhi and being a rag to help the collapsed world.