Hitotsu no Kabe

Manaka-kun and Risa-chan are inseparable childhood friends, with Risa being one school year ahead of Manaka. But this means that starting this year, Risa will be in middle school, whereas Manaka will still be in elementary. How will this affect their friendship? Edit: Note, Chapter 1 was entitled ひとつの壁 (One Wall), whereas Chapter 2 was entitled 追いかけっこ (Playing Tag). The author has not given the series a formal title yet.