Image 1: I just did some looking and in Ch. 82 Gege first explained the history which suggests that there is a Binding Vow at play with the technique when passing down this technique, so that only family may learn the technique. Could be a mistranslation, but idk.

I wonder if Miwa and Kusukabe are related somehow... 🤔🤔🤔

Image 2: Based on the dialogue in chapter 82, it sounds as though Mechamaru was never directly taught how to use the technique and that he learned it by observation.

Image 3: I'm not sure, but it's likely that Mechamaru had to resort to an unorthodox method of utilizing Simple Domain (via the tubes) due to not learning it officially, which could be in relation to the possible Binding Vow placed on learning the technique.

Image 4: I also think it's awesome that Mechamaru basically had eyes and ears everywhere, just soaking in information.

Image 5: I just realized, that Kenjaku basically stated what his plan for Shibuya was in this chapter. Unless I'm misinterpreting.

P.s. this utilized Viz translation. I'm going to re-read JJK under a different translation eventually.