Pretty simple story in which a dwonky kid meets a ghostly being who assists him in hunting monsters that are invading from another dimension. In this case, he goes up against a Medusa, Nessie, and a version of the Yuki Onna. Whenever he defeats one of the monsters, if anyone else encountered it in the real world, their memories of that encounter are erased.
(Spoilers) The last of these stories, with the Yuki Onna, is really sad--I was quite surprised at how sad it was, as it involved an older fellow who had adopted the Yuki Onna, and ultimately (even though the "monster" was not really bad), they had to exterminate the kid, and the man (who had adopted her) completely forgot her afterwards.
Not great, but very easy Japanese, so it's good practice.
This entire review has been hidden because of spoilers.