Saredo Tsumibito wa Ryuu to Odoru

It is a world replete with dragons and Jushiki sorcerers. Jushiki is a devastatingly powerful formula that can alter the laws of physics, capable of creating enormous TNT explosives or poisonous gas through plasma and nuclear fusion. A down-on-his-luck sorcerer named Gayus joins forces with the beautiful but cruel Jushiki practitioner, Gigina, as bounty hunters pursuing dragons. Then one day, they are presented with an odd request: to serve as security guards for a grand festival put on by Mouldeen, the ruler of their kingdom. It is then that a mysterious serial killing of Jushiki sorcerers begins.

(Source: TBS Global Business)