This shade of pea soup green is officially the best color for notebooks. Bonus, the super-smooth paper inside is a treat for writing, it lays nice n' flat when open, and its unique grid/lined hybrid paper makes for massive adaptability.
We generally try not to be pushy with the upselling, but this clear cover is inexpensive and is just perfect for your A5 Midori notebook. Grab the pair and you have a notebook set that will really be an absolute joy.