NAGATORO, Saitama Prefecture--A popular winter tradition here, “kotatsu-bune” boats equipped with kotatsu leg-warming floor heaters offer a warm respite from the winter chill. The rides are ...

YANAGAWA, Fukuoka Prefecture--Taking a boat ride in the depths of winter may be the furthest thing from most people’s minds. But fear not, operators are offering tourists “kotatsu-bune ...