The manga centers on the relationship between a middle school teacher who has a knack for gal games and a 14-year-old "perfect prospective wife" who is and expert on the Sengoku period.

Koe de Oshigoto! is a story about Aoyagi Kanna, a 16 year-old girl who was asked to become an ero-ge seiyuu* on her 16th birthday by her 28 year-old sister at her ero-ge company. Can she do the job properly while she's still innocent and inexperienced?

*Note: ero-ge seiyuu means erotic game voice actress.