Who is Prince The Ripper?

"Prince the Ripper" is one of antagonist's from Japanese manga & anime "Kateikyoushi Hitman Reborn".

His real name is "Belphegor" nicknamed "Bel", he is a member of the infamous mafia assassination squad known as "The Varia" and he holds the varia strom ring

The fact that he's royalty (a prince from a far off country) and he's considered to be an genius in assassination with knifes being his choice of weapon is what earned him the name "Prince the Ripper".

I tried to give you enough info without the possible plot spoilers just in case you intended to watch "Reborn" yourself... hope I succeeded...