Complex sentence: Pierrot announced on April 12,2014, exactly 8 years since their disbandment, that they will perform two shows at the Saitama Super Arena in October 24 and 25.
Split into simpler sentences: Pierrot announced on April 12,2014, exactly 8 years since their disbandment, that they would reunite for two shows. The concerts were held at the Saitama Super Arena on October 24 and 25.