To borrow the words of Keigo Higashino: "There is no specific reason for the severance of friendship between people. Even if there is one on the surface, it is probably just the result of the heart leaving, and it is just an excuse made up afterwards. Because if the heart has not left, when something that will lead to the breakdown of the relationship occurs, someone should work hard to save it. If not, it means that the relationship has already broken down."
This book tells the anecdotal story of Xiao Fei, an ordinary girl with no background, no talent, and no cheating.