Tamatebako
The Tamatebako is a box that is said to contain the power to make anyone grow older. It was in the possession of the royal family of Fishman Island and was stored in the treasure room of Ryugu Palace. Vander Decken IX once planned to use the box to make a young Shirahoshi older in order to have her age match his so that he could marry her. However, Decken abandoned the plan when he learned that there was no way for him to enter the palace. It was first mentioned by the Flying Pirates in Jinbe's flashback. After the defeat of Hody and Decken, the soldiers discover that all the palace treasures and the Tamatebako, a national treasure, had been stolen. It is later revealed that the Tamatebako was also rumored to "make one as strong as a thousand men". Both of these rumors are true, as the box contained the Energy Steroid, which gives the user incredible strength, but if heavily abused, it ages them horribly. The Minister of the Right later told Neptune that he filled t...