Haruka Tomatsu
For the first 14 episodes of season one, the opening theme song is "Crossing Field" by LiSA, and the ending theme song is by Haruka Tomatsu. From episode 15 onward, the opening theme is "Innocence" by Eir Aoi and the ending theme is "Overfly" by Luna Haruna. The main theme for "Sword Art Online: Extra Edition" is by Aoi.