User blog comment:Sinister 00/About 666/@comment-162.198.48.128-20140130000940/@comment-1359322-20140130011332

Otaku.....no not going to say anything.

"Regarding 666, he’s the “Beast” that appears in John’s Apocalypse alongside Great Red (the Red Dragon). Also, its name and the setting is D×D’s original."

- Volume 16 Afterword