U+3191 Ideographic Annotation Reverse Mark

The Wikipedia has the following information about this codepoint:

Kanbun (漢文 'Han writing') is a system for writing Literary Chinese used in Japan from the Nara period until the 20th century. Much of Japanese literature was written in this style and it was the general writing style for official and intellectual works throughout the period. As a result, Sino-Japanese vocabulary makes up a large portion of the Japanese lexicon and much classical Chinese literature is accessible to Japanese readers in some resemblance of the original.