His vocal register is described as a metallic lyric tenor suitable to voice a mature variation of coming of age young men.
Combined with an impactful execution on battle cries, he earned his reputation in voicing heroic protagonists commonly found in works of the mecha, fighting, and fantasy genres.
[8] When the time came for Hiyama to plan his career development during his senior year of high school, he resorted to the mindset of "if I had to bread-win, might as well choose the type of bread that I love to eat.
[9] Due to the tough application requirements of his intended history major,[9] Hiyama decided to pursue the path of voice acting, and talked it over with his parents.
[11] He also noted to have part-timed as a security guard for a short while, and mentioned how he deliberately hid his face in case his colleagues spot him out during a period where he has to overlook a construction site near his recording studio.
[9][14] Hiyama received his first official role as the principal villain character, Syndrome in Chikyuu SOS Soreike Kororin, a 1992 environmentalist anime television program spanning a half-year recording schedule.