This is a GREAT manga full of mysteries and EXCELLENT art + storytelling.
It follows the story of Emilyko, the living doll, and her shadow, Kate. Emilyko has to clean every single day all the soot that comes out of Kate, but why is it? What's soot? Just what is a living doll? What does it mean to be "a face"? What even are shadows?
They live in a mansion owned by the Shadow family. Little by little you (and them) learn about their surroundings and context. What is that mansion, though? What on earth is the Shadow family anyway?
Chapter by chapter you gather new questions while finding new answers, it keeps you hooked. The more you read, the more new and interesting characters are presented and more questions arise.
At first it may seem very light and wrote only for the aesthetic, but the plot so far is very interesting and gets deeper by the chapter (and it is also consistent! which is not actually quite easy to find). It has a nice pace, good characters, great story and, mostly, it's beautiful. I love it, I absolutely recommend this manga to anyone, really.
UPDATE: it seems a Shadows House anime has been confirmed. I recommend reading the manga anyway, because it is just exquisite, don't miss it.