You learn something new everyday. The Japanese word for a shell-matching game is slang for tribadism. Doesn't really translate over to English at all. "Let's match our clams together" ?

I'm changing the translation to give more sense to the term Kaiawase being misunderstood since "scissoring" has no context in the final image.

funny that in spanish, we use the term "shell" (concha) as a vulgar slang of vagina.

Fendo said:

funny that in spanish, we use the term "shell" (concha) as a vulgar slang of vagina.

I'd rather say that it refers to the vulva, but I wouldn't say that anyone takes into account such details.

On topic: I love Midna's expression in the last koma.