secret notepad

It looks like a black paper... If you write something you don't want other people to know in black pen At first glance, you can't see it, But if you look closely If you look closely, you can see that the words are written on the paper. It is a one-stroke letterhead in the style of a trick in a detective drama. The top one is a “Secret” note. and “Please keep secret” at the bottom. The bottom part is printed in a thin layer of ink. (The letters are clearly visible in the image, (The letters are clearly visible in the image, but in reality, they are so thin that they may or may not be visible.) If you use a silver or other metallic pen (The letters are clearly visible in the image, but in reality, they are so thin that they are barely visible. You can use a black pen to secretly convey your secret. Or you can use a silver pen to make your message clear. Please feel free to use it as you like.