The Koh-i-Noor is the world's largest natural colorless diamond mined from India. Its uncut form is said to weigh 186 carats. Within the British royal family, the diamond was rumored of bringing bad luck to any man who wears it.
"Once called the world's largest diamond, it was cut when it came to the British royal family. It is said to bring bad luck to any man who wears it, so only the females have ever adorned it."
—Persona 5 Compendium
Koh-i-Noor is encountered in Okumura's Palace and Mementos' Path of Adyeshach' floors 1 to 4, 6 to 8 and 10 to 12. The most effective way to capture this Shadow is by Downing it using Physical attacks with High critical rate, such as Lucky Punch or Miracle Punch.