Complex sentence: In 2015 Gyze organized the Vanishing Heaven Fest introducing Korean and Taiwanese metal bands to Japanese fans; later this year Gyze shared the stage with the American band Unearth.
Split into simpler sentences: In 2015 Gyze organized "Vanishing Heaven Fest", introducing Korean and Taiwanese metal bands to Japanese fans. Later that year, Gyze shared the stage with the American band Unearth.