Monster Musume no Iru Nichijou

Before monster chicks crowded in, Kimihito Kurusu led a quiet, nondescript existence by himself because his parents were away. The cutting-edge Japan of this parallel reality is the first nation to support the societal integration of non-human creatures. The newly minted "Darling" immediately draws girls of various breeds, leading to an ever-growing harem flush with eroticism and attraction. This is because Agent Smith, the interspecies exchange coordinator, was incompetent and left Kimihito in charge of Miia, a Lamia, in her homestay. The Interspecies Exchange Act unfortunately for him and the girls forbids interspecies sexual activity! The lone exception is made by a test marriage clause. The ferocious, affectionate, and lusty ladies pursue Kimihito at every turn, vying for his romantic and sexual affections, making his life complicated by a wealth of creature-specific caveats and delicate interspecies law. Where Kimihito and his harem go is anyone's guess because new species frequently develop and things sometimes just happen.