It is the night of a festival in Mahana, the central village of Hakolo Island. Rathalos all around the world are vanishing.
You are the grandchild of Red, whose Monstie was Guardian Ratha, the revered protector of Hakolo Island. Upon setting out to gain experience as a Rider, you encounter Ena, a Wyverian girl who once knew Red. In order to protect the egg that Guardian Ratha has entrusted her with, you decide to leave the island together.
There are strange things happening everywhere. As you try to figure out what is causing these environmental abnormalities, the egg finally hatches. A flightless Rathalos with small wings bursts out of the egg.