Shoujobyou 少女病("Girl Disease").
Shoujobyou produces a big sound featuring mythic stories sung by two women, with an orchestra built around twelve violins, and including narration by seiyuus. Previous seiyuus have included Sawashiro Miyuki, Ono Daisuke, Toyosaki Aki, and Hanazawa Kana.
Shoujobyou began as a doujin (self-released) group, but seems to have become Lantis's answer to one of Ao-chan's favorite groups, Sound Horizon. And in addition, it does anime and game music, such as an ED for Katanagatari.
The new album was released at Comiket last month, and is one of the group's own doujin works, rather than a Lantis album. Here are a couple of samples from tracks on the album, which is called Melophobia of the Holy Relics 聖骸メロフォビア.
The first is called "Flower Shaking in Ecstasy on High":
The second is "Rusty Red":