Saredo Tsumibito wa Ryuu to Odoru - 12 ᴴᴰ

The series takes place in an alternate world, staged mostly in the city of Eridana, whose territory is half in the Tseberun Dragon Empire, and half in the Lapetodes Seven Cities Alliance. Each half is separated by the Orielal River. In this world, special abilities called spell formulas (咒式, jushiki) exist, which are essentially chemical reactions augmented through special weapons that cause a magic spell-like effect. These special weapons are called Magic Staff weapons, and are as varied as regular weapons are. Spell formulists use these spell formulas to fight with "Beasts of Abhorrent Form," natural creatures that use spell formulas and pose a threat to humans, such as Dragons, Aions, or Enormes. The story focuses on the two main characters, Gaius Sorel and Gigina Ashley-Bufh, the only two employees of spell formulist dispatch office Ashley-Bufh & Sorel Co. They are met with a variety of requests from a variety of clients, all requiring the adept use of spell formulas.