In a narrow back alley in Tokyo lies a café called Funiculi Funicula. In the café, customers have the opportunity to travel back to a time of their choosing, as long as they follow a long list of rules. There is only one seat in the café that allows time travel; the seat is only available when the ghost that usually occupies it goes for a toilet break; once back in time, customers can't leave the seat; the only people in the past who can be met are people who have visited the café; whatever happens in the past, the present won't change; and, most importantly, the customer has to return to the present before their cup of coffee goes cold (around 1 hour).