Brown is called Chairo in Japanese. Kasshoku and Kuriiro are also used, but Chairo is the most commonly used.
In writing, it is often written as 茶色, 褐色, and 栗色. But the kanji characters for 褐色 and 栗 are a bit difficult, so you can also write them as かっしょく and くり色.
In Japanese, Chairo is also commonly described as the color of tree trunks, soil, chestnuts, and chocolate.
In the Muromachi period, tea leaves（茶Cha） decoction began to be used as a dye, and along with this, the name Chairo was born.
Chairono juutanwo kounyu shimasu
“I buy a brown carpet.”