Murai Munenobu served as a bushō during the Azuchi-Momoyama period. He had the other name of Shinemon-no-jō.
Munenobu was the younger brother of Murai Sadakatsu primarily engaged in governing affairs in Kyōto after the arrival of Oda Nobunaga in the capital.
On 8/7 of Tenshō 3 (1575), acting as a representative of Sadakatsu, Munenobu recommended to the Akaibō in Toga-no-o that the tokuseirei (an order to cancel debts to lenders and money brokers and return lands to temples) apply to the landholdings of the Tokudaiji family. Munenobu’s name also appears in land survey records for the Koga manor from 1574 as the individual responsible for tax collections.
Munenobu had friendly relations with a noble and Shintō priest named Yoshida Kanemi, meeting frequently from around 1575. When, on 1/14 of Tenshō 4 (1576), Kanemi came to visit, Munenobu received a gift of 30 hiki (= 300 mon) worth of coins. Meanwhile, Murai Sadanari (Munenobu’s nephew and Sadakatsu’s eldest son) received a gift of 50 hiki while another family member named Murai Seizō received 20 hiki, reflecting the relative social status of those involved. On 2/17 of the same year, Kanemi visited Munenobu to request a discharge for road construction so Munenobu served as an intermediary with Sadakatsu to permit the request.
Munenobu also went to Kanemi for personal matters. On 3/6 of Tenshō 8 (1580), he discussed with Kanemi a request from Sadakatsu for a pine tree.
On 1/17 of Tenshō 10 (1582), Munenobu helped in the preparation of a banquet at the Daitoku Temple in Kyōto to report the naming of a high priest to the Emperor.
On 6/2 of Tenshō 10 (1582), Akechi Mitsuhide launched a coup d’état against Nobunaga in an event known as the Honnō Temple Incident. During the event, Munenobu, together with other family members including his older brother, Sadakatsu, and Sadakatsu’s sons, Murai Sadanari and Murai Seiji, fought from Nijō palace against the Akechi forces, but was killed in action.