Manga by Fairy Tail Mangaka "MASHIMA Hiro", totally unrelated to Fairy tail Manga though.
The story takes place in a fictional world full of monsters and adventurers called Monster Hunters, who, as their name implies, hunts these monsters. The plot revolves around a young Monster Hunter, Shiki, whom was taken in as an apprentice to a Monster Hunter named Gurelli as a child. A few years after Gurelli's death, which was due to a gunpowder incident, he comes back to his master's residence, Akamaaya Town, to join the guild there. In that guild, he meets a girl called Irie and after a series of events, he finds that she is the daughter of his master. From this point onwards, they form a party to find the legendary Miogaruna, which was Gurelli's life-long ambition.