Seijo no Maryoku wa Bannou desu

The Kingdom of Slantania performs a ritual to summon a Saint who can cleanse the miasma spawning monsters across the land, but the spell brings two women from Japan instead of one. The prince immediately chooses the other girl and leaves 20-year-old office worker Sei Takanashi with no clear role in the palace.

Sei does not mind for long. Rather than wait for recognition, she joins the Medicinal Flora Research Institute and immerses herself in herbs, potions, and magic. Her creations soon prove far more effective than anything an ordinary researcher should be capable of, and a chance encounter brings her close to Albert Hawke, commander of the Third Order of Knights. The quieter life Sei hoped for becomes harder to preserve as her abilities increasingly suggest that the kingdom chose the wrong Saint.