In a small basement coffee shop in Tokyo, four customers receive the chance to travel back in time, but the rules are strict: they can only go to the past, they can only meet people who have visited the café, they cannot leave their seat, and whatever they do, the present will not change. Toshikazu Kawaguchi's novel explores what happens when people accept these limitations and travel anyway. A woman wants to see her former lover one more time. Another hopes to read a letter her husband wrote before his memory failed. A sister wishes to reconcile with a sibling who has died. A mother seeks to meet the daughter she never knew. The constraint that the present cannot change distinguishes this time travel story from those premised on altering history. The journey back can offer closure, understanding, forgiveness, but not different outcomes. Kawaguchi, who originally wrote the story as a stage play, creates an intimate setting where characters must confront their pasts in a single conversation before their coffee gets cold. The novel has become a phenomenon in Japan and internationally, spawning sequels and adaptations. Readers seeking a meditation on regret, acceptance, and the limits of what we can fix will find this gentle fantasy affecting.