Koyomi Yamanaka (山中 暦, Yamanaka Koyomi) is a main character in SSSS.Dynazenon. He is an implied NEET and cousin of Chise Asukagawa who became one of three co-pilots of Dynazenon (the other being Yomogi Asanaka and Yume Minami).
As noted by Gauma, Koyomi is quite perceptive despite outwardly lazy and has little things to do beside standing in front of his computer. True to this, he not only managed to master his Dynastriker, but also quick to analyze Greyjhom's combat abilities.
Koyomi has brown hair, with bangs which over both of his eyes almost all of the time, but when you can see his eyes, they are shown to be light blue. He wears a light green jacket with black and yellow stripes on either sides of the sleeves. He wears black sweatpants with yellow stripes on the sides along with orange sandals.