Ota

Ota has more public bathhouses than any other of Tokyo's 23 wards, and a large share of them draw on kuroyu — black hot spring water. As of January 2026 the ward has seventeen hot spring facilities, again the highest count in the 23 wards.

The water is black because of humic acid, formed as ancient seawater, plants and algae were buried and broke down underground. Visibility runs to about 10cm, and where the concentration is high it drops below 3cm. Most of it is weakly alkaline at pH 8–9, which leaves the skin smooth. First-time visitors often think the water is dirty. Locally it is a point of pride.

Around Kamata the food is dense too. Hanetsuki gyoza — dumplings with a lacy skirt — began in this neighbourhood, and three tonkatsu houses are grouped together as the gosanke, the big three. Their lineages connect, yet each differs in batter and in how the cutlet is cut, and locals will tell you which of the three they belong to.