If you look to the stairway on the left, you can see a concentration of stones, each roughly the size of a human head. A stone foundation was originally built above these stairs, however, it was later removed between 1901~1903 in order to create the stairway, and the stones hidden behind the foundation became exposed.
Thus, in the days when the tall, stone foundation was still intact, the only way to get into the castle was through the second gate located behind.
If you walk up the stairs in the back, there is a section that’s called "sanmaru." According to a drawing of Hamada Castle’s stone foundation, there were originally walls built on top of the foundation from "sanmaru", all the way up to "honmaru" located on the hillside. However, there were none built on the stone foundations from "sanmaru" down to Nakanomon Gate. It’s said that walls were only built on the stone foundations near the summit, which were clearly visible from the surrounding area. Due to this, it is regarded as "Castle to Show."