Below is an 1894 Japanese map of Korea called the "Jissoku Chosen Zenzu" (實側朝鮮全圖) by So Mokan (宗孟寬). The map is housed in the National Assembly Library of Korea.
A closeup of the map shows two islands off the east coast of Korea. The island nearest the Korean coastline is labeled "Ulleungdo -Takeshima" (鬱陵島 竹島), which has a small neighboring island just off its west shore labeled as "Ulsando" (亐山島), which was one of the misspellings for "Usando" (于山島). To the southeast of Takeshima is another island labeled as Matsushima (松島).
This map is important in the Dokdo-Takeshima debate because it shows Ulsando (亐山島) as a neighboring island of Takeshima (竹島 - Ulleungdo) while also showing a separate island much farther to the southeast labeled as "Matsushima" (松島).
Koreans claim that the Japanese believed Usando (于山島) to be the Japanese island of Matsushima, which was the old Japanese name for Liancourt Rocks, but this map and others (1875 Japanese Map & 1882 Japanese map) are evidence that the Japanese believed Usando to be a neighboring island of Ulleungdo, not Liancourt Rocks. In fact, all Korean and Japanese maps shows that Usando was just a neighboring island of Ulleungdo, not Liancourt Rocks.