Complex sentence: They are most well known for their song, which was used as an ending theme for the of Naruto Shippuden, and their song "Rashisa" (らしさ), which used as an opening theme for Barakamon in 2014.
Split into simpler sentences: They are most well known for their song, which was used as an ending theme for the of Naruto Shippuden. And their song "Rashisa" (らしさ), which used as an opening theme for Barakamon in 2014.