Where is My Bride Is a Mermaid set?
Japanese manga series
My Bride Is a Mermaid (2002): 1 real place Wikipedia files it under as its setting, in Japan. Wikidata records no setting for this manga at all, so this is a category rather than a statement, and it is labelled that way below. Where the manga takes place, not where it was made: a manga is drawn and filmed nowhere, so this is the only kind of location it has.
Places per Wikipedia: “Television shows set in Saitama Prefecture” category
Wikipedia’s “Television shows set in Saitama Prefecture” category lists 1 place. A category is an editor’s choice, not a sourced sentence, so these places are listed apart. Each links to its category.