Issei Masamune was a Japanese narrator and voice actor born on December 2, 1948, in Kure City, Hiroshima Prefecture. He began his career in 1971 after being inspired by the narration of城达也 on a radio program. He initially worked under his real name, Michiro Okada, before adopting the stage name Issei Masamune in 1978. He retired from television and radio work on December 2, 2018.

Masamune was widely known for his deep, calm voice and worked extensively as a narrator across various television programs and anime series. He is particularly famous for his narration in the early Japanese versions of the Transformers franchise, including Transformers: Scramble City, Transformers: The Headmasters, and the film Transformers: The Movie. In these same series, he also voiced the character Soundwave, and later Soundblaster. His narration work also extended to tokusatsu dramas, notably as the narrator for Kamen Rider Black and Kamen Rider Black RX.

In the Armored Trooper Votoms series, he voiced the character Ru Shako, appearing in the original television series, as well as the OVAs Armored Trooper Votoms: Big Battle and Armored Trooper Votoms: Phantom Arc. His film credits include a role in the 1984 film Kuroi Ame ni Utarete.

Other significant voice roles throughout his long career include the Section Chief in the You're Under Arrest series, Paulo Cassius and Gaia in Mobile Suit Gundam, and Dwight Greenhill in Legend of the Galactic Heroes. He was also active in providing Japanese dubbing voices for foreign films and series.

Throughout his career, Masamune was part of several talent management agencies. He was a founding member of Sigma Seven and later established his own agency, Munku, in 1997.