A story of the bond between a mother and a son who begins living alone after completing his university entrance exams. A son bids farewell to his nosy but loving mother and the home of his memories. A mother's heart is touched by the final "thank you" she hears from her son. The day of parting. Looking back on their memories, the father and son become lonely... However, there is a big secret behind the mother's tears... By the time I finished watching it, it was already late. A human mystery mystery-solving comedy where you can't get "a certain word" out of your head.