ケース (Case) refers to a grammatical category that indicates the relationship between a noun and other elements in a sentence. In languages like Japanese, cases help clarify the role of a noun, such as whether it is the subject, object, or indicates possession. Different cases can change the form of a noun or pronoun, providing essential information for understanding the sentence structure. In Japanese, common cases include が (ga) for the subject, を (wo) for the object, and の (no) for possession. Each case marker is attached to the noun, guiding the reader or listener in interpreting the intended meaning. Understanding cases is crucial for mastering sentence construction in Japanese.