Asahi is making plastic bottles of water that are meant to be served hot. They're being marketed to people who don't want coffee or tea, but still want to be warmed up with a hot beverage on a wintry day. The bottles will be sold in convenience stores.
One day, someone will invent an insulated bottle that keeps liquids hot or cold. Until then, buy these plastic bottles of hot water from your local convenience stores.
From Japan Today:
"Sayu" just means "hot water," and the piping hot bottles are simply filled with the same mineral water that Asahi usually sells at cold or room-temperature under its Oishi Mizu Tennensui. Asahi says in recent years hot water has been gaining in polarity, with a growing number of people craving it on late-autumn and winter mornings as a way to warm themselves up without the jittery caffeine side effects of coffee or tea.
These aren't just leftover bottles of water that get tossed into the heater rack, either, as orange caps indicate that a drink, under Japanese beverage-handling regulations, is only to be sold hot.