It's a family crest with 3 oak leaves drawn in a circle.
 
The Yamauchi family crest has oak leaves that are distinguishably thinner than oak leaves in other designs.
 

What is oak leaves?

• Oak is a mysterious tree; even when it is classified as deciduous, it won’t lose leaves until new leaf buds come out. This led oaks to be regarded as good-luck trees that will continuously thrive through generations.

 

Castle's name that stamp this family crest

・Kochi castle（Kochi）
・Kakegawa castle（Shizuoka）
 

Yamauchi Kazutoyo