Sanpei's wife, Otsuu, recently passed away and his son, Shirou, offers Sanpei to live at his place with his daughter-in-law, Reika, and granddaughter, Nona. Ever since Sanpei married Otsuu, she has taken care of him and Sanpei has never learned how to cook, clean and other household chores. After going through his late wife's belongings, Sanpei finds a book that she was writing that records all the things she was doing for him. Things from recipes and how to do household chores to dealing with the family that he has never really connected with. Now with the help of the late Otsuu's book, Sanpei learns how to do all the things she did for him and start making connections with the closest family members he has.
Most readers might not be able to directly understand Sanpei's struggles of losing a wife after so many decades. However, you may have a grandparent that experienced that kind of tragedy and Sansanroku will help you put yourself in their shoes. A very heartwarming manga.