Kanon

From SCX-Scans:

An alternate retelling of KEY’s classic work, Kanon, where it asks: what if Yuuichi DIDN’T lose all his memories of 7 years before? And what if he was really sarcastic? Do NOT read if you don’t know the original story behind Kanon.

The second manga, under the main title Kanon was adapted from the visual novel version that preceded it, and was illustrated by Kensha Shimotsuki. The first bound volume was released in Japan on April 1, 2007 and focused on Nayuki's story.  There are four chapters in volume two, one for each of the other heroines not featuring in volume one, starting with Makoto's thirty-eight-page chapter, followed by Mai's with eighteen pages, Shiori's with twenty, and finally Ayu's with forty-eight pages.
(Source: abridged wikipedia)