[Osaka no Jin⚔Sacred place pilgrimage] There is also a well said to be Sanada's loophole at Isshinji Temple, right in front of Yasui Shrine where Nobushige Sanada died.
The “Sanada family = loophole” also exists in the famous Ueda Castle and Yasui Shrine/Sanada Maru, so it is a must-see for pilgrims to sacred places.
【大坂の陣⚔聖地巡礼】
真田信繁が最後を迎えた安居神社の目の前の一心寺にも真田の抜け穴といわれる井戸があります⚔

“真田家＝抜け穴”は、他に有名な上田城や安居神社/真田丸にも抜け穴が残っていますので、聖地巡礼に必ず。