Before Your Memory Fades - BY Toshikazu Kawaguchi

In a small back alley of Tokyo, there is a café that has been serving carefully brewed coffee for more than one hundred years. Local legend says that this shop offers something else besides coffee—the chance to travel back in time.
Over the course of one summer, four customers visit the café in the hopes of making that journey. But time travel isn’t so simple, and there are rules that must be followed. Most important, the trip can last only as long as it takes for the coffee to get cold.
Heartwarming, wistful, mysterious and delightfully quirky, Toshikazu Kawaguchi’s internationally bestselling novel explores the age-old question: What would you change if you could travel back in time