A nice collection of monsters from Japanese folk lore. The monsters are also unique and broad enough to be able to adapt to other types of campaigns. Though a few spelling / formatting issues exist here and there, the document itself is put together and designed nicely with authentic Japanese art used as the illustrations. A title page would have been nice, perhaps explaining a bit about the Yokai and how they fit into Japanese culture and how to adapt them to various type of games.
The monsters themselves are wonderful. The Kappa are turtle like imps that like to wrestle and take the Shirikodama (souls) from creatures . The Yuki-Onna is spirt that resides in colder / snowy climates. With her spellcasting and snowstorm aura, the Yuki-Onna makes for a very interesting monster mechanically and thematically. I could see this being utilized in many campaigns that have a cold climate.
The Omukade is the biggest and most feared of the Yokai. A little more could go into describing the appearance of the monster (as it is not quite clear in the picture provided) and it is a bit hard to grasp what the creature looks like. Other than that the creature is designed quite well and the rage/legendary action mechanic is interesting and the creature itself could be used in other campaigns.
Tsukumogami are household objects that have been neglected for too long and become animated. The Karakasa is presented here, an mischievous one eyed umbrella. I found this monster to be quite fun and the Tsukumogami quite neat. We end the collection with the Oni. These Oni are a bit darker in theme than their Monster Manual counterparts, having a cannibalistic type approach, making for a pretty terrifying creature, that can be used in replacement or even side by side the MM version.