Momiji is a character that appears in For Honor's Singleplayer Campaign.
An old friend of The Orochi, Momiji was a Nobushi among the three who broke them out of prison during the Great Raid. She helped defend the city and drive out the Vikings. After the Emperor's death and Seijuro's appointment, she and The Orochi infiltrated the palace to help let the troops in to overthrow the newly appointed emperor. Once this was done, she and The Orochi go to Ashfeld to find the location of the fortress of the Blackstone Legion. They run into the Iron Legion and Momiji is injured while trying to escape. The Orochi manages to help her get away.
Momiji was a very bubbly individual who seemed to be amazed at everything whether that be facing down the Seijuro's elephant or scouting a 'creepy castle'. Though not an Orochi, she still had the infiltration and scouting skills to operate like one.
Coincidence or not, she does share her name and weapon with Ninja Gaiden character Momiji.