The Real Steel 686 was introduced in the 1980s. The Marushin 586 is a worth replica as it certainly looks the part and could deceive people into believing it's real, though we wouldn't want anyone to attempt that feat.
The Marushin 686 is a Black Heavyweight weighing in at about 570 grams and its made out of ABS plastic. It certainly looks like you're holding the real deal. However, shooting it is a different situation.
Airsoft guns coming out of Japan are not the most powerful as they do have a lot of restrictions. This one fires at 200fps with HFC Gas and 250 with Green Gas. This is something we can only find out since we're out of Japan. It's relatively accurate but I wouldn't say what appeals to most of us.
It may not shoot how we want it to shoot, but it does look incredibly beautiful as it's something collectors could add to their Airsoft Arsenal.