The box set contains the three volumes of "Kuro".

Being the only inhabitant of a huge building, Coco would have felt extremely alone if her beloved black cat, Kuro, hadn't been there. Although the cat has its quirks, the two are an inseparable couple and have fun adventures every day.
Lulled by the bliss of these idyllic days, Coco is not entirely aware of the sad reality that surrounds her: for all the other inhabitants of her city, life is full of fear and anxiety; they fear the sinister forces that envelop their city, but they also fear Coco and Kuro.
Unaware of everything, Coco lives peacefully with Kuro, but her days of blissful ignorance may quickly end...