Sachiusu is a fairly simple manga, but it is amusing and cute. The humor parts of it aren't laugh out loud funny, but they have their moments. The main gags, that Mukai is unlucky yet cheerful and her classmate Misako is lucky but weird, comprise most of the panels and the humor. They don't really have much to them beyond those simple character traits and they don't really develop much, but for a single volume 4-koma, I don't really consider that to be a major problem. If the manga continued beyond a single volume, the simplicity of the characters and the singular focus on the reoccurring gags would probably lose their charm.

The art isn't anything spectacular, but neither is it overly problematic. It's probably on the level of your average 4-koma. A minor spoiler, the story (to the extent there is one) doesn't have any real resolution, and if you were hoping for any kind of explanation as to why the MC is unlucky, you won't find one.

As it is, as long as you're not expecting anything grandiose from it, Sachiusu is a kind of cute, kind of funny story that's not a bad way to kill some time with.