This series probably needs no introduction, but for newer anime and manga fans that are unfamiliar, Tenjou Tenge was the first hit manga by Ito Ogure, writing under the pen name Oh! Great. He would later create Air Gear and a pair of hentai works: Silky Whip and Naked Star.
Tenjou Tenge manga (10 volumes, ongoing)
The manga itself is began with some iffy artwork and a SHITLOAD of nudity, but as the manga ran it’s course and turned into a major commercial success, the nudity was gradually tuned down while the art and action (and by action, I mean shockingly graphic brutality) journeyed to very high heights.
Sometimes you see mangaka start up in hentai and through talent and commercial success eventually transition with success to mainstream manga. The line between hentai and non-hentai manga is just so thin compared to hentai animation and anime that transitions like this are incredibly common in the industry.
Oh! Great has my admiration for starting off with a mainstream manga success and then after that moving on to hentai projects. This is not a guy who needed an easy paycheck. He did it for the love of the game, so to speak. As a huge fan of ecchi and hentai manga, I think that’s pretty cool.
This manga also spawned an anime by the same name in 2004, which appropriately was the same year that Ikkitousen debuted. Unfortunately, the Tenjou Tenge anime wussed out and kept things strictly non-nude. I don’t think that every ecchi series necessarily needs to have boobs in it, but for a manga that felt like porn in the early volumes, going the non-nude route seems like a pretty big betrayal of the source material.