Overman King Gainer is a 2002 series, brainchild of Yoshiyuki Tomino aka Gundam man. The whole thing just feels like Turn A Gundam, same art style, similarly non-conformist mecha designs but this has uber fast pacing and I don’t even notice each episode zipping by. In the OP, the Overman, the eponymous King Gainer, has a scene where he does the Monkey. You know, that dance where you clench your fists and keep your elbows straight, knees bent, shake your butt and move the arms up and down. Totally organic haha. The figure was a May 2005 Max Factory release. It also has an alternative colour scheme, the Akiman scheme. Haven’t got far enough in the anime to know what the hell that is. 
King Gainer stands about 18 cm tall and has a chainsaw sword cum rifle accessory. It can be attached to his hip. Note that he is non-poseable and stands there like a bouncer outside a nightclub. Max Fac has done a great job as usual, with very clean lines, no paint smudges or any defects whatsoever. The figure is heavy too, about 2-3 times as heavy as a typical girl figurine. Besides that, there is nothing to talk about. Except that it has dreadlocks. Mecha with hair… organic. Normal price is 6000 yen, but I was ripped off for 99 bucks at Latendo. I give it a 70. I feel ripped off, as news of another release of King Gainer filters through. The new release apparently is poseable. ARGH.
Seems like there have been virtually no King Gain figures released, aside from this brick and some gashapon sets. You mentioned rumors of a poseable figure? I’d love to know more about that.
What is coming out is the Anna Medaiyu + flying King Gainer set and the Kaiyodo OKG action figure. Kaiyodo will have a US release so wait for that. Please see the figure news section.