How would you say younger twin sister in Japanese?

There isn't a single perfect translation for "younger twin sister" in Japanese that captures the nuance of "twin" directly. The best approach depends on the context. Here are a few options:

* 妹 (imōto): This simply means "younger sister." If it's clear from context that she's a twin, this is sufficient and the most natural choice.

* 双子の妹 (futago no imōto): This literally means "twin's younger sister." It's more explicit about the twin relationship.

* 下の双子 (shita no futago): This means "the younger twin." This is a good option if you want to emphasize the twin aspect and that she's the younger one. However, it could sound a little formal or less natural in casual conversation.

In most situations, 妹 (imōto) will suffice, especially in casual conversation. Only use the more explicit phrases if you need to emphasize the twin aspect.