Hayama Hotel Otowa No Mori

The infinity pool faces Sagami Bay and runs on natural hot springs, so you're soaking rather than swimming, which feels like the right call. This hotel and resort sits in Hayama, long a retreat for Tokyo's well-heeled and the Imperial Family, and it carries that quiet prestige without announcing it. Earth-tone interiors, Acqua di Parma in the bathrooms, views toward Mount Fuji, and a French restaurant on the premises round things out rather nicely.