Matsunaga is a Clan in Nioh.
The Matsunaga clan helped the Miyoshi clan conquer the Kinai area of central Japan and claimed Yamato province (present-day Nara prefecture) as their base. Their most famous member was Matsunaga Hisahide.
Hisahide was a valued advisor to Miyoshi Nagayoshi and proved his worth in many campaigns, including the one which drove the Ashikaga shoguns from the capital. Before long, however, his forces threatened to overwhelm the Miyoshi clan itself, and he repeatedly clashed and formed uneasy truces with key Miyoshi retainers. He was notorious for his shocking, brutal battle tactics, including the time he burned down the Hall of the Great Buddha at Todaiji Temple. Eventually he offered fealty to Oda Nobunaga and claimed a domain of his own, but after repeated betrayals was killed by Nobunaga himself.
The family crest "Tsuta" depicts an ivy leaf. Ivy is known for its hardiness and ability to find purchase anywhere, not unlike the scheming and determined self-made daimyo that was Hisahide himself.