What makes Oblivious by Kalafina notable?

'Oblivious' quickly gained traction as it became the opening theme for the anime series 'Kara no Kyoukai,' significantly boosting the group's visibility. The single's success helped solidify Kalafina's place in the J-pop genre and led to a broader acceptance of their unique baroque pop style. Released on January 23, 2008, 'Oblivious' was Kalafina's debut single, marking their entry into the music scene after forming in 2007. At this point, they were still establishing their identity as artists under the guidance of Yuki Kajiura, known for her work on anime soundtracks.