Oiwa お岩 is an elderly woman with very short, dark purple hair and wears a green yukata. As a stand user, she can take the stand of her deceased husband Tagosaku タゴサク into her own body, still retaining her own consciousness. When she does this, she undergoes a transformation, growing over twice her own size and becoming much stronger. Her face also turns white with purple linings around her eyes and nose area.
First portrayed as a humble and kind-hearted old woman, Oiwa お岩 looked like she didn't know anything about the lingering spirits. However, it lated turned out that she knew all about them, and also knew how to control them using peanuts, and use them as a means to battle with. As a child, Oiwa would start seeing spirits. Whether she was happy or sad, the spirits would always be there for her, and when humans couldn't be at her side, the spirits would be there for her instead. She wanted to give them a paradise, to at least allow them to enjoy a hot spring before passing on, and so she created the Senboukyou. She soon had many souls coming to the Senboukyou before reaching heaven, and just to see them smile before passing on gave her a sense of satisfaction. However, after her husband passed away, she realized she had been alone all along, and started forcing the spirits to stay at her inn, instead of sending them to the afterlife, so that she wouldn't have to worry about being alone anymore. Later on, after grasping the consequences of her wrongdoings, she regretted her actions and apologized to all the lingering spirits in the Senboukyou, eventually causing them all to ascend to the afterlife, except for Rei, who stayed behind to help her run the inn.
Oiwa お岩 lost her parents at a very young age. That's when she started seeing lingering spirits. She had an one sided love to Terada Tatsugorou, this caused a rivalry between her and Otose but she loses to Otose.
Later she met her husband Tagosaku and would later create a hot springs bath deep within the mountains to try and give the lingering spirits a place of comfort and rest before they went to the afterlife. She originally ran it with her husband, and an orphan named Rei, but now only runs it with Rei who has become a lingering spirit.