Looking for romance manga (it'll likely be shoujo or josei) with a haraguro male lead. The tag is fairly unused so just in case people don't know:

A Haraguro character is one who has an outward appearance of being amicable, friendly, innocent, kind and/or refreshing, but uses any combination of the aforementioned traits to hide their real cruel, cunning, evil, manipulative, mean and/or sadistic side.

Despite the negative connotation, not all haraguro are villainous or are sociopaths. Their motives vary very widely depending upon the character her/himself and the "seriousness" of the story.

The paradigm for this archetype is Chihiro from Omake no Kobayashi-kun and Otona no Kobayashi-kun.
Other examples include:
Sangatsu Owaru - Watanuki-san ni wa Boku ga Tarinai
Souta - Ouji-sama ni wa Doku ga Aru.
Keishi - Joshi Mousou Shoukougun
Haku Reishou - Ookami Heika no Hanayome

I'll add more as they're suggested. Although ideally, they won't be hiding their personality (Like Haku, Keishi, and Souta do). I prefer them to be a bit more on the sadistic side as well, but beggars can't be choosers.

Cheese in the Trap is suppose? The main guy in it is possibly a sociopath.

well its not really a romance but i think Sun from Legend of the Sun Knight would fit pretty well. It was originally a novel too if your into those.

and Rood from Black Haze I think has his moments like this as well

[img]http://24.media.tumblr.com/3b280fafb72cad0f718be64368e64ca7/tumblr_myylzmuiY41rw3pzao4_250.gif[/img]
Like educational manga? take a look at Ed U. Manga's list of manga here

The love interest in Ookami Shoujo to Kuroouji comes to mind, as well as the guy from Kaichou wa Maid-sama.

There's also a side character/harem member in Kamisama Hajimemashita who fits this trope (he's a literal snake), and the initial-love-interest-turned-antagonist in Akatsuki no Yona.

I suppose Livi from Soredemo Sekai wa Utsukushii could also be considered this, though in his case he's more just a smug king and doesn't care who knows it.

It is short, but Akuma de Koi Shiyou comes to my mind. The male lead does bad things secretly, without harming others however.

Kare kano

Dame Daze... Zen Zen Dame Daze

koroshi ai

There’s this haraguro tag, but yeah, not much selection there. I do personally recommend Inuwashi Momo wa Yuruganai, hated the male lead, but I’m sure he fits the bill.

I'm in idol hell T.T