From a Kuota's website about the Khan frameset:
The Khan is, in two words, wickedly stiff. It is also incomparably nimble and agile. These characteristics are due to the hand-laid 100% carbon fiber tubes and Kuota's DDC (Dual Drive Concept) wishbone seat stays and the integration of Kevlar on the drive side chain-stay. While carbon can be compressed, it does not stretch (think of those Chinese finger games you played as a kid); but Kevlar, on the other hand, has just the opposite properties, namely, it stretches but does not compress. When you blend Kevlar and Carbon together, you have a composite material with ultimate rigidity. Hence, the use of both carbon and Kevlar where they're need most.