I built this guy about six years ago (as well as the rest of his team) and even wrote a short story around him (I was originally going to write an epic, and I built the Toa team central to it). Short story shorter: During an epic battle to save his land, after his other five Toa teammates have fallen, he releases a nova blast of ice, stopping the threat but being encased in a cocoon of ice. Now, millennia later, he has thawed (Captain America-style), only to have icy protrusions become a part of his armor, affirming his icy nature.
The team of six I built is not his original team that perished, but a new team he has become a part of. More details to follow when I finally take decent pictures of all six.
Is Koji a good name for a Toa? I seem to think so.