Okama is an artist who combines artistic talent with an evident flair for design; his portfolio as a designer in the world of anime now dwarfs his original works, though in my opinion they do not fully approach what he accomplished with the likes of Hanafuda, though this is perhaps unfairly applying my own taste – he is not really a pure mangaka, more of an artist, and he certainly is not restricted to the erotic themes I am focused on here.
The work I am going to focus on to the unfair exclusion of all his other work is the magnificent full colour erotically themed manga 華札 / Hanafuda, which manages to combine captivating full colour illustration with a well crafted story and a careful appreciation of the setting, as well as some varied and extremely erotic content (a lot of it, in fact). It is a masterpiece.
Since it includes more oni, here are the CGs from Angelic Works 20, from TECH GIAN; it will save you knocking her clothes off yourself.
Regarding his many other other works, he has done a lot of work recently in more collaborative roles such as character design for anime and the like, as well as producing general manga (notably “Cats”, “School” and “Cloth Road”), but these works fail, to me at least, to impress in the same way Hanafuda does, although this is obviously simply a consequence of taste. His earlier dojinshi are also rather plain.
His artbook “OKAMAX” is worth checking out, but since it lacks a single theme or story it is not compelling in the same way Hanafuda is, at least to me.
Food Girls is a rather interesting manga like work which defies easy description.
Okama is undeniably skilled, popular, and I can certainly recommend Hanafuda as a superb example of his work, as well as an excellent stand alone work. Considering how prolific he is, it is quite possible you have at any rate already seen some of his work unwittingly in the form of character design, but seeing some of his works here hopefully illustrates his abilities rather more emphatically.