This was so great in the beginning, but the end was so rushed. This is just one of many testaments to the bad effects axing has on a good piece of literature.
From what I can tell about some of the blurry parts of the story, Kari is a boy who was about to be sacrificed on an island, but he escaped the ritual and got his powers, fleeing to were he is in the story now and beginning to experiment on dolls and stuff (which he likely turned them into those puppet things by accident, since he was lonely and probably just wanted the dolls as something to stave of the loneliness and stumbled upon his power of what is essentially animating things). Maggie at the time is just a doll, one which the Professor played with as a child, and after his mother went ol' brain consumption game on him the doll was lost. Then Kari found Maggie as a doll and incorporated her, a pin, and whatever else you need for a zomviguarna to make the person version of her. But it seems that anything used in the creation of a zomviguarna tends to keep memories of their previous use/life regardless of whether or not they were inanimate objects, so Maggie had memories of happily being played with by the Professor as a doll. With those memories, she started yearning to be with him again, which angered Kari, causing him to deem her a failed creation, then cutting her up and throwing her away. Then Professor finds her and stitches her up, runs away from his guardian, and we start from chapter 1, or chapter 1 happens a little after some undisclosed minor events.
From what I can glean from the story, a zomviguarna is made using 4 components, and the pin is something that seems to only be produce-able by Kari. The zomviguarna are made of a corpse, a random item or object (or more corpses as seen with the cat), a pin, and a ghost. I think a ghost is used because that is how the Professor re-animates Maggie in the end. The pin seems to be something used to anchor the ghost to the body's brain and synchronize the brain and ghost's will, making sure that the brain doesn't develop into another person. The corpse is obviously used for a body, with the object/item's use being unknown to me, but the item/object does seem to both provide the zomviguarna with a power, and add to their look.
Hope this helps anyone looking for an explanation to the two topics (Kari and his connection to Maggie, and how zomviguarna are made). Zomviguarna is a great manga, I just wish people in Japan would apply their progressive social and technological ideas to their literature, or we'll keep seeing more creative, unique, and interesting ideas for manga and perhaps light novels be axed.
