Called chirori (銚釐, glance: meaning that it heats up quickly), this aluminium jug is the traditional instrument with which, in more authentic places such as oden bars and ryōtei and especially in winter, sake is heated in a bain-marie in Japan, ingeniously using the handle to place it on the edge of a pot full of hot water (not boiling hot!), which could also be the one in which a warm rice porridge is prepared.
Being careful not to burn yourself, the very familiar gesture to check if the temperature was the correct one was to take the small jug and place the bottom on the hand, measuring very empirically.
In this regard, the rattan-coated handle makes it safer to handle it without getting burned.
The unit of measure of the jug is in gō (合), that is to say the single portion of rice used in antiquity to pay wages, which is nothing but the square wooden box in which sake is served today.
Each gō is about 170cc, so this jug (3 gō) contains about half a liter.