User blog comment:B214/DxD Zero: Sirzechs story/@comment-2601:8C:601:5692:10CB:3C3A:1054:FC5-20180620183547

Yosh! Anyone note the chapter name?

▪Ruin Prince [紅髪の滅殺王子（ルイン・プリンス）]

I'm fairly sure we have Sirzech's former title/nickname. Though, in the story it'll probably read in romanji as "Benigami no Ruin Purinsu" and thus be "Crimson-haired Ruin Prince", matching his mom's and sister's nicknames.

Also, I suggest the new character's name should be:

▪ Bidræd Basharn Beelzebub [ビドレイド・バシャルン・ベルゼブブ]

The first name aside, you're missing the final N in the second name.

By the way, thanks for the translation.