It's Already Ancient Times, Why Are There Still Unspoken Rules?

Su Feifei, a male, was an overtime maniac who worked hard to get a promotion. The day before his promotion, he died suddenly after drinking. He traveled into the body of a baby and learned that he was an illegitimate child. Ever since he started growing teeth, he has been tested for poison and medicine by two old monsters. He almost died once, but as a blessing in disguise, he was revived by Old Man Wang and gained a lot of internal strength... This novel and its characters are purely fictitious. Any similarity is purely coincidental and should not be imitated.