After chap 3.5, you should read the 1st chap of Kuroha to Nijisuke: Kuroki Majo no Divertimento before continuing to chapter 4 http://www.mangago.me/read-manga/kuroha_to_nijisuke_kuroki_majo_no_divertimento/hs/hs_v-1-chapter-1/
After chap 3.5, you should read the 1st chap of Kuroha to Nijisuke: Kuroki Majo no Divertimento before continuing to chapter 4
http://www.mangago.me/read-manga/kuroha_to_nijisuke_kuroki_majo_no_divertimento/hs/hs_v-1-chapter-1/