The "Chrono" (時空 Jiku "Spacetime" in the OCG) cards are an archetype of cards used by Chris Yurai that support his various " " monsters. They specialize in creating Xyz Monster combinations with " " monsters, as well as speeding up the process of summoning " " monsters. They also have a subtype of powerful Xyz Monsters called "Chrono LEGEND" (時空ＬＥＧＥＮＤ Jiku Rejendu "Spacetime LEGEND" in the OCG) All "Chrono" monsters, save for "Number T: Chrono Star Jiffy" and most of the "Chrono LEGEND" cards, are either LIGHT or DARK.
The "Chrono" monsters themselves are all TIME monsters, and they share a lot of similarities with the " " archetype, as they all appear to be various creatures and figures from different time periods and dimensions, but possessing strange technology. The "Chrono LEGEND" monsters take this even further, appearing as upgrades to their original forms with strange highly-advanced armor, as well as different-colored tubing corresponding to their Xyz Material colors connecting the armor pieces. However, all of the "Chrono" monsters possess the same symbol of a glowing white circle with part of it taken out, with two lines going to the center at each endpoint of the broken circle. These lines correspond with either 11-o'-clock or 5-'till-midnight.
The "Chrono" monsters are tied to the "LEGEND X-Cel!", which turns normal " " monsters into a new concept called "LVX". They can also protect weaker " " monsters so they can more easily grow and thrive on the battlefield through a subset: the Dimensional Sigil Spell/Trap cards." archetype. They use an assortment of various methods to help the " " monsters get to their full potential, as well as exceed that power through the mysterious card "