Mitsui Memorial Museum in Tokyo. In several halls, the show documents the appearance of yokai (spirit creatures, ghosts, demons) in works of art going back hundreds of years. There are paintings, books, Noh masks, manga, and even little musical instruments representing those played by yokai.
There is also an entire room showcasing original art by Mizuki Shigeru, best known for his seminal work GeGeGe no Kitaro. Dozens of drawings are shown, with familiar characters by Mizuki.
There are some English explanations, but most are in Japanese. Still the exhibition is worth checking out to see the art and get a sense of the continuity of yokai in Japanese culture - a presence which carries on today.
Photos were not allowed inside, so sorry about the text-only description. You can see photos of some of the exhibits on the museum's website here.
Click here to see a PDF (in English) with the full list of exhibits.