Araki Muratsugu served as a bushō during the Azuchi-Momoyama period.  Muratsugu was the eldest son of Araki Murashige, a retainer of the Ikeda clan in Settsu Province.  Muratsugu wed Rinko, the daughter of Akechi Mitsuhide, a senior retainer of Oda Nobunaga.  Muratsugu later separated from Rinko and she re-married with Akechi Hidemitsu, a retainer of Mitsuhide.

After the Ibaraki clan was eliminated at the Battle of Shiraikawara on 8/28 of 1571, Murashige appointed Muratsugu to serve as lord of Ibaraki Castle in Settsu, while the de facto lord was Nakagawa Kiyohide, a senior retainer of the Araki clan.  In 1577, Kiyohide became the official lord of Ibaraki Castle and Muratsugu moved to Amagasaki Castle (formerly Daimotsu Castle).

In 1578, Murashige’s unexpected rebellion against Oda Nobunaga triggered the Siege of Arioka Castle.  Muratsugu helped defend the castle in support of his father, but the defection of Nakagawa Kiyohide to the Oda turned the tide against the Araki.  On 9/2 of 1579, Murashige escaped to Amagasaki Castle.  Nobunaga promised to the Araki retainers, including Araki Kyūzaemon (later known as Ikeda Tomomasa) who had taken over defense of the castle after Murashige’s departure, that if the defenders vacated Amagasaki and Hanakuma castles, he would spare all of the women and children. Leaving the women and children in Arioka as hostages of the Oda, Kyūzaemon and others traveled to Amagasaki Castle on 11/19 to convince Murashige to accept the proposal, but Murashige refused, whereupon Kyūzaemon abandoned the hostages in Arioka and fled.  A defiant Murashige joined Muratsugu in a move to Hanakuma Castle, held by Araki Motokiyo.  This led to the Battle of Hanakuma Castle.  Murashige then defected to the Mōri clan and lived in the town of Onomichi.

In 1582, Toyotomi Hideyoshi rose to power after the Honnō Temple Incident, a dramatic coup d’état launched by Akechi Mitsuhide against Oda Nobunaga that resulted in Nobunaga’s untimely death.  Hideyoshi forgave Muratsugu for his past transgressions and allowed him to become a retainer.  In 1583, Muratsugu participated in the Battle of Shizugatake, but injured his leg and did not participate in later conflicts.  His younger brother, Araki Muramoto, served in his place.  Thereafter, Muratsugu resided in Ōsaka and occasionally met Hideyoshi.  After the demise of Hideyoshi, Muratsugu died while in the middle of being hired to serve as a retainer of Tokugawa Ieyasu.  The year of his death is uncertain, but he was thirty-eight years old, meaning he was born around 1561.