The Mu Family was a clan of warriors that descended from Mushin himself. Only their bloodline is capable of accessing Mushin's Legacy. According to Yehara, she knows of only one last descendant of Mushin making them the only heir to Mushin's Legacy.
Some of the Mu Family was said to have lived in Clear Sky Village, however the Mu Family as a whole were all wiped out during the Stratus-Talus War. All of them, except for Yesana, Yehara's sister, who was with child at the end of the war. Yesana herself was not of the Mu Family, but she married Muyong who is one of Mushin's descendants and had ties with the Shadowless soldiers. She did not learn this until after their child was born. Muyong was killed during the war against the Talus Dominion, but she had no time to mourn as the very next day, assassins showed up to erase the very last of the Mu Family and claim all of Mushin's artifacts for themselves.
It was widely believed that Yesana was killed by the Grimhorn, but Yesana fled with her baby daughter to the swamps where she passed by Shadowless agents and begged for help, but they had betrayed the Mu Family and kill her instead. Many also believed that Yesana's daughter also died in the attack. However, as Yesana tried to reach for her daughter as she bled out, a man named Yunsang appeared and took the young baby as his own. The baby would grow up as Yunsang's daughter, Yunwa, and heir to the Lumang Syndicate.
Her spirit remained near Lotus Lake within a large lotus flower where she was slain. When the hero releases her spirit, she appears before Yehara and the hero to explain the events leading to her death. She passes on to the Divine Realm, finally at peace, letting her sister know that she still loves her and her daughter dearly. Her lotus flower is then moved to Clear Sky Village to be left in Jang Jongwon's care.
The Mu Family was also in charge of keeping the Silver Crest which is one of two crests required to activate Mushin's Wings, a mechanical bird that leads the heir to Mushin's Tomb which contains his Legacy.