Kondo sees "tidying" as a cheerful conversation in which anything that doesn't "spark joy" is thanked and ceremonially sent on its way. The result can be life-changing, she says. Clients find themselves surrounded by things that provide clarity, unencumbered by belongings that carry past baggage (unwanted gifts, clothes that no longer fit) or anxieties about the future (does anyone need that many cotton swabs?). Even her book, she says, should be discarded when it's no longer needed.

Part of what makes her method unusually speedy is that instead of decluttering room by room, she tackles a household by subject. So, the clothes, then the books, then documents, then miscellany and, last and most difficult, photos and mementos. Instead of deciding what to discard, she says, the focus should be on which few things spark sufficient joy or are truly necessary.

How to contend with family members unready to join in the celebratory purge? Kondo advises against secretly disposing of their things. "You can leave communal spaces to the end. The first step is to confront your own stuff."

She then turns to organising what's left. The key, she says, is storing things mostly in drawers, arranged so that everything can be seen at a glance.

Kondo says she has been obsessed with "tidying" since she was five, opting to arrange shoes and pencils in school while other kids played in the playground. She began communing with her belongings in high school and, after years of work at a Shinto shrine, realised her calling as a professional consultant on attaining the joy of minimalism.

"The inside of a house or apartment after decluttering has much in common with a Shinto shrine … a place where there are no unnecessary things, and our thoughts become clear. It is the place … where we review and rethink about ourselves."