The blue color of Koromo seem to gradually grow darker as the koi grow older. Accordingly, the blue color of seemingly right tone in small koi often becomes too dark when the koi grow big, and the blue color showing right tone on big koi, on the other hand, were in many cases overly light tone when the koi were still small. This fact, therefore, should be taken into careful consideration when buying Koromo. This categaory includes all koi with shiny body but devoid of any markings. As they don't have any markings, the condition of luster and body conformation become the essential points for appreciation of Hikari-muji group.
Excellent luster is the one which covers the whole body eveyly.
Generaly, koi of Hikari-muji group readily get used to humans. With hearty appetite, they tend to grow over-sized bellies. However, good shape body, covering from the head to breast and abdomen. The point of appreciating this group is of course the intensity of the Hikari, the very characteristic of the Hikarimono group. Their markings are similar to those of Showa Sanshoku and Utsurimono group mentioned before.