Sentō are urban public baths where people bathe entirely naked, men and women separated, through an ingenious succession of hot, cold, foaming, electrified and perfumed pools. Far more than places of washing and relaxation, they are essential to the Japanese social fabric; yet despite that deep anchoring, sentō face great difficulties and many close each year. To understand their decline and what is at stake for them, the authors spent three months inside the sentō of Kyoto.