Ok kiddo, so Japanese citrus is like fruit that grows in Japan. There are many different types of fruit that grow in Japan, but some of the most famous ones are oranges called mandarins and lemons called yuzu.
Now, mandarins are easy to peel and taste sweet and juicy, kind of like a fruit snack. Yuzu, on the other hand, is super sour and bitter, kind of like a mix between a lemon and grapefruit. But even though yuzu is super sour, it's often used in Japan to make things like tea, noodles, and even perfume!
So, the next time you hear someone talking about Japanese citrus, just remember that it's like yummy fruit that grows in Japan, and there are many different types with unique flavors!