Complex sentence: On September 30, Girl's Day made their Japanese debut with the album "Girl's Day 2015 Autumn Party", which contained Japanese versions of the singles "Darling", "Twinkle Twinkle" and "Ring My Bell".
Split into simpler sentences: On September 30, Girl's Day made their Japanese debut with the album "Girl's Day 2015 Autumn Party". It contained Japanese versions of the singles "Darling", "Twinkle Twinkle" and "Ring My Bell".