▁singles ▁on ▁it . ▁However ▁it ▁was ▁decided ▁that ▁a ▁best ▁of ▁album ▁was ▁needed ▁and ▁so ▁they ▁were ▁released . ▁Four ▁days ▁following ▁the ▁dual ▁album ▁release , ▁the ▁group ▁launched ▁the ▁‘ p ops aur us ’ ▁tour , ▁visit ing ▁ 1 0 ▁cities ▁and ▁playing ▁ 1 5 ▁shows , ▁last ing ▁from ▁July ▁ 1 5 , ▁ 2 0 0 1 ▁all ▁the ▁way ▁through ▁September ▁ 2 5 , ▁ 2 0 0 1 . ▁A ▁month ▁into ▁the ▁tour ▁their ▁ 2 0 th ▁single ▁ ▁was ▁released ▁and ▁used ▁to ▁promote ▁the ▁be verage ▁. ▁Two ▁months ▁after ▁the ▁pop sa urus ▁tour ▁ended , ▁" Y outh ful ▁Days " ▁was ▁released . ▁Re leased ▁on ▁November ▁ 7 , ▁ 2 0 0 1 , ▁it ▁was ▁their ▁ 2 1 st ▁single ▁and ▁was ▁an ▁insert ▁song ▁for ▁the ▁Japanese ▁drama ▁. ▁It ▁ended ▁up ▁being ▁their ▁best ▁s elling ▁single ▁for ▁the ▁year . ▁The ▁b - side ▁for ▁the ▁single , ▁" Drawing ", ▁originally ▁had ▁no ▁commercial ▁tie - in , ▁but ▁two ▁years ▁later ▁was ▁used ▁as ▁the ▁theme ▁song ▁to ▁the ▁ 2 0 0 3 ▁Japanese ▁drama ▁. ▁ ▁Mr . ▁Children ▁released ▁their ▁ 2 2 nd ▁single ▁ ▁on ▁January ▁ 1 , ▁ 2 0 0 2 , ▁which ▁was ▁used ▁as ▁a ▁show ▁song ▁in ▁the ▁Japanese ▁drama ▁. ▁Four ▁months ▁later ▁their ▁t enth ▁original ▁album ▁It ' s ▁a