Angel Core: Tenshi-tachi no Sumika / ANGEL CORE エンゼル・コア～天使たちの住処～

This first entry in the Angel Core series follows a young soldier (fighting for a fictional, futuristic empire) as he's transferred to a secret military installation, where's he surprised to discover that his new job will be having sex with gorgeous young "Angels," a group of genetically unique women who need regular intercourse to nurture their powers....