SHOCK3 is the final installment of the shock series created by Terkoiz.
The animation starts with Mr.Red, the series' protagonist having a cigarette, when his boss, Mr. Dark Green asks him to walk with him. While walking, Mr. Dark Green tells Mr. Red that it's employee checkup day, and he creates multiple clones which start the battle. As the two of them battle, Mr, Dark Green creates so many clones that Mr. Red eventually loses track of the real Dark Green.
Red tries multiple stratagies to find the real Green, until he eventually sees that one of them is looking in the other direction. he believes that it is the real Dark Green and eventually defeats him, only to realize that it's just another clone. Mr. Dark Green says that not only could he not locate the real him, but also failed to keep the field tidy, and with that, Mr. Red is fired.
The epilogue explaines that ever scince he was fired, Mr. Red has been serching for a new master to control him, and that a SHOCK4 will never be created.