"Let's make this formal, I am the Apartment's finest cosplayer - Red Mage Rosa Wollaston."

Like his friend Crom, Rosa is a cosplayer who dresses up like a video game character most of the time, but unlike him who is a jerk who dresses like a hero, Rosa is a nice guy who dresses like a villain, to be exact this guy for no reason beyond his outfit has roses and rhodium is named after roses, the quote up there is even a reference to this as it is based on what the guy says when you fight him. In addition, Rosa is somehow the richest person in the apartments as rhodium is prone to massive price spikes, to the point it's sometimes the most expensive element by far.