On the other hand, kaiawase as a game similar to the card game 'Concentration' used to be called "kaioi," but it later became mixed up with the other one because of its hand movement of putting shells together, and came to be called by the same name of kaiawase.
一方、「神経衰弱(トランプ)」に似たゲームとしての貝合わせは貝覆いと呼ばれていたが、殻を合わせる所作から後に混同されて、同じく貝合わせと呼ばれるようになった。