Memory Days is an anime-only Magic Item.
Memory Days appears to be a thick silver hardcover book with four hearts on the cover, arranged to resemble a four-leaf clover. These hearts are filled with small hearts of red, blue and white. Green triangles can also be seen surrounding the hearts and the title which is printed below the hearts with a ribbon underneath. The contents of the book are written in fine print with the four-leaf heart separating them from each other.
The book causes a person to go back to the time that they cannot want to remember. However, if someone else touches that person, they will also be transported to the past. The book's effect lasts for six hours, and after the six hours pass, the person will be transported back to the present. If the people who touched the original transportee aren't touching them just before the return trip to the present, they will be forced to stay in the past.