Memento mori is a Latin phrase meaning "remember your death." The phrase is in essence a positive message, because it serves as reminder to people to take full advantage of their limited time on earth (if death comes so soon, live it up while you have the chance.) As a phrase, "Memento mori" was originally used in ancient Rome to remind victorious military leaders to be humble. Later, it was adopted by the emerging Christian church, and was used widely throughout the Middle Ages and the Renaissance, and spawned a genre of art aimed at reminding people of their mortality. The Memento mori concept appears in many different forms across the world's cultures, but one example of a Memento mori-style tradition that is still robust today is the Mexican holiday Dio de los Muertos, or "Day of the Dead," in which the spirits of deceased ancestors are welcomed back home to their families among much celebration and festival. The history of the Memento mori concept is a long and fascinating one, so if you are interested, I recommend doing your own research.

1. This is a reference to a line in the Bible, in Isaiah 22:13, which reads, "eat, drink, and be merry, for tomorrow we die."
2. The word here is "aishiau," which usually means "to love one another" or "to make love." However, Imai turned it into a pun by spelling it with the kanji "ai" (love), "shi" (death), and "au" (together), so I have translated it accordingly. It's not an obscure worldplay but it's a rather beautiful one.