This is the special chapter of Ruin Explorers that was printed as part of Kunihiko Tanaka’s OneVisions Volta artbook. As far as I can tell, it’s the last Ruin Explorers chapter ever written, and there’s no sign in sight for any more.
Ruin Explorers OneVisions Volta Chapter
Welp, there’s nothing left for me to do but to slowly work on translating the RPG.