Books in the Ragna Crimson series in order

In this action-packed dark fantasy, humanity lives under the threat of annihilation by immensely powerful dragons. The dragon hunter Ragna embarks on a revenge-fueled quest to eliminate that threat once and for all!Together with the Argentum Corps, Ragna and Crimson face off against a swarm of dragons led by Olto Zora, the Mad Maestro Dragon, and Taratectra, the Explosive Dragon. It’s Ragna’s one-hit-kill sword versus Taratectra’s devastating blows, with the outcome of the battle hanging by a thread. Then the Mad Maestro springs a surprise attack against the Argentum Corps base, placing the entire force in peril!