What makes Naisho no Hanashi by ClariS notable?

The title track 'ナイショの話' served as the opening theme for the anime series 'Nisekoi,' significantly boosting its popularity and visibility. This single helped solidify ClariS's reputation within the anime music genre, paving the way for future successes and collaborations in the industry. Released on February 1, 2012, 'Naisho no Hanashi' marked ClariS's first single after their debut album 'BIRTHDAY' the previous year. The duo was still relatively new to the J-pop scene but quickly established themselves as a significant force in anime music, with their sound appealing to a broad audience and contributing to their growing popularity.