Onsen Tamago Maker, On-Tama Gokko, Large, for 4 eggs. This is an onsen tamago maker. Onsen tamago are difficult to make with a microwave or other methods. With On-Tama Gokko, you can easily make onsen tamago just by pouring hot water. Pour hot water into the container, close the lid, and then wait for the specified time. You can make up to 4 onsen tamago at a time. Used only once.