Kaminari masterpost (to the best of my ability; there may be harder-to-find Kaminari content on the webcomic author's DA. i didn't scour it)

THE MANGA
https://rain.thecomicseries.com/comics/33
https://rain.thecomicseries.com/comics/64/
https://rain.thecomicseries.com/comics/71/
https://rain.thecomicseries.com/comics/72/
https://rain.thecomicseries.com/comics/455
https://rain.thecomicseries.com/comics/654 (this is the manga summary linked in the previous comment)
https://rain.thecomicseries.com/comics/931 (only the first panel of this page is about Kaminari)

THE ANIME
https://rain.thecomicseries.com/comics/785
https://rain.thecomicseries.com/comics/1334
https://rain.thecomicseries.com/comics/1402 * (linked in above comment)
https://rain.thecomicseries.com/comics/1403 *
https://rain.thecomicseries.com/comics/1404 *
https://rain.thecomicseries.com/comics/1406
https://rain.thecomicseries.com/comics/1407

In-Universe Fancontent and other derivatives
https://rain.thecomicseries.com/comics/631 (in-universe fancomic cover)
https://rain.thecomicseries.com/comics/672 (main webcomic character's dream combining the Kaminari setting/feel with other webcomic characters (the dreaming character's friends and family); continues through all of chapter 25, ends at https://rain.thecomicseries.com/comics/692 )

In-Universe ambiguously connected fandom
https://rain.thecomicseries.com/comics/1296
https://rain.thecomicseries.com/comics/1297