At the beginning of the game, in shibuya, if you interact with a certain crevice between two buildings you are able to talk with a so called "wizard". This wizard will ask you for 3 dices in exchange for an important secret. You are able to collect the 3 dices throughout the gameplay in the 3 districts before the shinjuku chapter, by interacting with certain npcs and buying the dices from them.
After the tv program side quest in yokohama, if you go back into the tv set you can find the same wizard from the beginning and give them the 3 dices. After the wizard reveals themselves, they give you a skill card for Dice and tell you to remember the word "lovestory", and that you'll know when to use it.