Sha la la☆Summer Time sold about 267K copies in the 1st week of release
http://www.oricon.co.jp/news/2077562/full/?ref_cd=tw
It sold more than Gravity's 1st week sales (about 213K copies)
Guess the different marketing strategy works even though I 1/2 heartedly feel Sha la la☆Summer Time doesn't deserve the high sales as it's not their best single imo