This 20th-century Japanese military is a striking contrast to the rest of the bric-a-brac in the Vatichino gallery. The flag was a gift from jiu-jitsu expert Uchimura Tengan to Isabella Stewart Gardner. He famously gave Gardner private lessons in jiu-jitsu. The “Hinomaru,” as the national flag of Japan is called, consists of a large red disk, representing the sun, in the center of a white rectangular horizontal background. Many of the gifts Gardner’s friends gave her were stored in the Vatichino, and remain there today.