In Japanese, Gray is called Gurē or Haiiro. We use both terms equally, but we tend to say Gurē more these days.
In the case of Gurē, hiragana is also written, but only katakana is used. Conversely, we use only kanji for Haiiro.
Also, gray is called Nezumiiro. Nezumi means mouse, and it means the color of a mouse.
Gurēna hibiwo okuru
“I spend my days feeling depressed.”
Gurē can also be used to mean hopeless, dark, and lifeless.
Kono businesswa gurēdakara kiwotsuketahouga ii!
“This business is legally gray so be careful!”
Gurē is often used when something is technically not illegal but morally wrong. For example, gurē na business is often used when talking about business.