Often times on Japanese releases, you'll see someone credited as plain "producer" and then someone else credited as "sound producer." From what I can gather from https://ja.wikipedia.org/wiki/%E9%9F%B3%E6%A5%BD%E3%83%97%E3%83%AD%E3%83%87%E3%83%A5%E3%83%BC%E3%82%B5%E3%83%BC, this distinction is used to distinguish the person who handled the actual audio production from the person who handled the administrative/human resources aspects of production.