In the game, the player controls A.D.A.M., a battle android, as he fights his way up a tower with eight floors, the first seven named after the seven deadly sins. It offers a sad, twisted, love story instead of androids gaining their "self".
While the main character shares his name from the previous title (which can be changed), they are two different characters. The game also features over 300 weapons, downloadable maps, and items, as well as wireless multiplayer for up to four people.
Rengoku 2: The Stairway To Heaven is actually based from the poem/story The Divine Comedy by Dante Alighieri.
Source: Wikipedia, "http://en.wikipedia.org/wiki/Rengoku_II:_The_Stairway_to_Heaven", available under the CC-BY-SA License.