Sachiko is a kind woman that deeply loves her family. She loves her husband, Soichiro very much and worries about his well being while he works on the Kira case. When Soichiro is hospitalized due to a stress related heart attack, she is frequently by his side to care for him. As concerned as she is about Soichiro, she also understands his convictions in working on the Kira case and she stays by his side. Sachiko is very proud of her son, Light and congratulates him on his good grades. When Sayu is wheelchair ridden due to emotional trauma caused by her kidnapping, Sachiko aides her recovery, encouraging her and taking her for walks outside.
Obata said that he had no real concept behind the design of Sachiko; he said that he encountered difficulty in drawing female characters who were not the main characters. Ohba did not include Sachiko in the final chapter of the manga, but stated that someone of the Task Force would likely tell her that Light and Soichiro died in order to stop Kira. The Task Force members would never let the world know the truth about the Death Note case.