Hotarugusa(螢草 菜々の剣)

Nana is a servant of the Kazahaya family, She is from a samurai family. Her father was about to reveal wrongdoings within the domain but had to commit ritual suicide for a crime he hadn't done. Ichinoshin tries to correct the wrongdoings, but end up being a target himself. After finding out her father's enemy is the man behind it all, Nana decides to protect Ichinoshin and his children, as she had promised Sachi, Ichinoshin's late wife.