Chinese script is logographic, Japanese only partially so. But a language is not its script. By approximation all modern languages that have been written have

Chinese script is logographic, Japanese only partially so. But a language is not its script. By approximation all modern languages that have been written have been written in the Latin script. That doesn't make them "similar languages" in any real sense. And conversely, many languages use several different scripts for the same language in different regions/groups depending on politics.