Akarui Kioku Soushitsu / Bright and Cheery Amnesia / 明るい記憶喪失
Rank: 5950th, it has 325 monthly / 9045 total views.
Authors: Oku tamamushi
Genres: Manga / Yuri / 4 koma / Comedy / Slice of life
Status: Ongoing
Summary:
From Girls in Boxes:

Mari's girlfriend, Arisa, loses her memories of the past three years, including all memory of their life together. However, it turns out that being crazy in love with someone transcends all realms of possibility.