本作は、すれ違う2人の姿を描く“再構築ラブストーリー”。技術職から営業部に異動して1年、口下手な加納彰人は職場になじめず孤独な日々を送っている。同期で営業部のエース・大狼誠司とはあるトラブルをきっかけに関係がこじれていた。ある満月の夜、彰人は神社で古びた鏡を見つけ「大狼とも対等に笑いあえるような、そんな自分になりたい」と願う。すると突然霧が立ち込め、彰人は“理想の自分”が生きる並行世界に迷い込むのだった。
                                             
                                    
                        A year after being transferred from a technical position to the sales department, Akihito Kanō, who is poor at expressing himself, struggles to fit in and spends lonely days. His relationship with his colleague and the sales department’s ace, Seiji Ōkami, had soured due to a certain incident.
One night under a full moon, Akihito discovers an old mirror at a shrine and wishes, “I want to become someone who can smile as an equal with Ōkami.” Suddenly, a thick fog appears, and Akihito finds himself lost in a parallel world—one where his “ideal self” lives.
                                                    
                            Aliases
                            
                                                                                                            - if no Sekai de Koi ga Hajimaru
 
                                                                                                                                                - Love Begins in the World of What If