Iron Heart 666-21 Review

Iron Heart 666-21 Review

When Shinichi Haraki started Iron Heart in 2003, he had motorcyclists in mind. That is to say, he knew that he wanted to design pieces that would guarantee longevity and accommodate a rugged lifestyle. Enter: the Iron Heart 666-21 (or, ‘the devil’s fit’). This 21oz slim-straight jean is a staple from the brand, and for good reason. Made in Japan’s denim district of Kojima, Okayama, this jean combines Western-inspired designs with Japanese craftsmanship. Keep reading for more detailed thoughts alongside some fit pics.


The Iron Heart 666-21 is a true slim-straight jean. The silhouette in the thigh is snug, and from the knee down, the jean does not taper. This makes the jean a great option for those looking for something to wear over a pair of boots, for example (see pictures below). The 666 has a medium rise too which means the jean sits comfortably just above the hips. Finally, the 666 (like all of Iron Heart’s denim) is made with a 36″ inseam to accommodate those who need the extra length. For those who don’t, see our page about hemming!

*For sizing, we recommend going up one tag-size from your regular size as this jean tends to fit on the smaller side.


You’d think that a jean made from a 21oz fabric would be uncomfortable to wear, especially at first. Not quite. Due to Iron Heart’s one-wash, sanforized processing, this fabric is very soft to the touch. (Learn more about Iron Heart’s fabric terminology). As a result, these jeans will be a comfortable option for those who are looking to enter into the heavyweight denim scene. Additionally, because of IH’s fabric processing, this jean will not shrink. In fact, this jean will stretch out between a half and a whole inch in the waist so make sure to size appropriately.

Fit Pics:

Final Thoughts:

The Iron Heart 666-21 is not for everybody. After all, it is made of an intimidating 21oz fabric. That alone makes this jean a tough one to wear in the summer months. And there’s no doubting a slim-straight fit is not for everybody. (In which case, check out IH’s other fits on our Iron Heart product page). With that being said, however, Iron Heart has made with this jean a quintessential slim-straight jean in both a durable and unique fabric.