This is the opening them for Sword Art Online, an anime that came out in 2011. There was a lot of good music in this show and this is one of those. With this album you get the full version of the song as well as the TV-size version, the opening credits version.
OK, I have to admit I have more than a small crush on Aoi Eir. This was my introduction to her and holds a special place in my heart for that reason. But it is GOOD. I'm becoming increasingly impressed by J-pop and this is indeed a fine example of the genre. Production values are high, the singing - aside from my crush on Aoi Eir - is excellent. I was extremely touched by the anime and listening to this song evokes all the memories I had of that excellent show.
There are two other songs on the album which also showcase Aoi's voice. 'dear brightness' (sic) is almost balladic. 'Velvet Tears' starts out like a rock-anthem, and, well, kinda finishes as one too. Both are immenently listenable. Yes, I am a native American English speaker and yes that is a legitimate sentence.
For us in America, spending ~$14 for 4 songs may seem a bit pricey, but that's the way J-pop is marketed. I find this to be a great value for the emotions the music evokes. I think you may find it so also.