>>282175830
Here is that segment of the 2019 interview on the subject:

"[Q:] On the other hand, Tamako's son, (Rinne's father) Sabato, is also a strong character. They say he's good-looking yet garbage (laughs). However, I was still impressed by the great character development that made it hard to completely hate him.

Takahashi: What he's doing is really trashy (laughs). But I had a lot of fun drawing that scumbag. There aren't many villains or enemy characters in Kyokai no RINNE, so I had no choice but to have Sabato play that role.

[Q:] Also, as I was reading the story, I was wondering why Rinne's mother didn't appear, but she makes an impactful appearance towards the end.

Takahashi: As for Rinne's mother, I had been thinking about bringing her into the story, but I had a hard time finalizing her character, and she ended up appearing only at the end of the story. When I came up with the idea of her being reincarnated and being younger than Rinne, I thought I had done it (laughs). As you know, this family usually lives separately, but in one of the last chapters, there was a story about a family trip that ended up happening, albeit by accident."