Doshisha Corporation, which plans, develops, and sells everyday household goods from its Osaka headquarters, is expanding its "Sayu Senka" lineup — a series built specifically for drinking sayu (water that has been boiled, then cooled to a comfortable drinking temperature), whose popularity has grown alongside a wider boom in onkatsu, or temperature-focused wellness habits. The new "ONDOZONE Sayu Senka Sayu Nomi" teacup goes on sale Wednesday, September 16, 2026, through Doshisha's official online store "Doshisha Marche" and mass retailers nationwide.
A built-in heat-absorbing material cools boiling water to a comfortable sayu-drinking temperature in about two minutes, then keeps that temperature for about 30 minutes.
Background
Doshisha launched ONDOZONE in 2017 as a brand built around the idea of "enjoying temperature," aimed at everyone who cares about temperature, offering the experience of "surprise" and a "new sensation." Since then, the brand has focused on developing products centered on managing the temperature of drinks and the sensation of warmth or coolness, always from the perspective of "enjoying temperature." In 2023, it launched the "Sayu Senka Mug Cup (320ml)" to meet demand tied to the onkatsu trend. It has since expanded the lineup with a 230ml mug, an electric kettle, and a pitcher, and by May 2025 the series had grown into a hit, surpassing 300,000 cumulative units shipped.
This time, to fit more lifestyles, the series is adding its first teacup-type item. Compared with the existing mug, the rim has been designed thinner for a more pleasant feel against the lips, and the shape has been made easier to hold, so the comfort of a traditional teacup supports a daily sayu habit.
Product Features
A structure suited for sayu
The product uses highly insulating stainless steel on both its inner and outer surfaces, with a heat-absorbing material placed between the two layers of stainless steel to cool boiling water to a temperature that is easy to drink. It has no lid for heat retention and no vacuum structure to block heat, so that the temperature drops more readily.
Sayu refers to water that has been boiled once and then cooled to a comfortable drinking temperature. Boiling once removes impurities and chlorine, making the water easier to drink.
Cools boiling water to a comfortable temperature, and keeps the warmth longer
Based on research among people who drink sayu, Doshisha considers 60 to 65°C to be the comfortable temperature range for drinking it.
Simply pouring in boiling water lets the heat-absorbing material draw off heat, bringing it down to a comfortable drinking temperature in about two minutes. Once it reaches that temperature, the heat-absorbing material and the highly heat-retentive stainless steel keep it at a comfortable drinking temperature for about 30 minutes. A typical stainless steel vacuum double-wall mug is still around 88°C after two minutes, and even a ceramic mug is around 78°C — both can be too hot to drink right away. With this product, even on a busy morning, pouring in boiling water and waiting about two minutes is enough to enjoy sayu right away, making it easier to keep up a daily sayu habit.
A series you can choose to match your lifestyle
Alongside the 320ml and 230ml Sayu Senka Mug Cups, the series now also offers this teacup type for the first time. You can choose between a mug or a teacup depending on your lifestyle and preference.
Warmth gently reaches the outside, too
The product uses a heat-absorbing structure developed specifically for sayu. Because of this, it doesn't just bring the drink to a comfortable temperature — warmth also gently reaches the outside of the cup. On a chilly day, cupping the teacup with both hands gently warms your hands as well.
Choose from three colors
The teacup comes in a lineup of three colors: ivory, green, and charcoal. These calm, understated colors blend into everyday life, so you can choose the one that fits your taste or interior.
Product Overview
| Item | Details |
|---|---|
| Name | ONDOZONE Sayu Senka Sayu Nomi |
| Model Numbers | OZSY200IV, OZSY200GR, OZSY200CH |
| Colors | Ivory, Green, Charcoal |
| Size (approx.) | W70 × D70 × H90mm |
| Weight (approx.) | 188g |
| Capacity (approx.) | 200ml |
| Suggested Retail Price | ¥2,480 (tax included) |
Ivory
Green
Charcoal
Official Website
https://do-cooking.com/sa-yousenka/
Recommended ways to drink sayu, supervised by onkatsu doctor Niina Ishihara, are also published on the official website.
