Guren sometimes appears to be indolent, but in truth, he really works hard just in areas other than official army meetings and instructing classes for examples. He keeps many secrets to himself, and has no difficulty lying about them. Concerning long term plans to dethrone the Hīragi Family, this, and his sleepiness, it is partially a result of a desire pressed on him upon being possessed by Mahiru-no-Yo.

Entering school accompanied by Sayuri Hanayori and Shigure Yukimi, he was wary of others learning about his capabilities since they were outright hostile to him on account of his family background. With thoughts of biding his time and undermining such house structures, particularly the Hīragi Family, he would be approached by Saitō and informed of the upcoming apocalypse event. He would be befriended by Mito Jūjō and Norito Goshi, along with Shinya Hīragi, where they were tasked by Kureto Hīragi of intervening against the Hyakuya Sect's plans.

Currently, Guren is a Lieutenant Colonel of the Japanese Imperial Demon Army, and the leader of the Vampire Extermination Unit's Moon Demon Company where he is the squad leader of the Guren Squad. After retrieving Yūichirō Hyakuya he promises him revenge against the vampires who have taken over the ruined world. Working closely with Shinoa Hīragi he also arranges for Yu, along with Yoichi Saotome and Shihō Kimizuki to acquire black demon Cursed Gear weapons. Adding Mitsuba Sangū as the fifth member, Guren would have them join him in Shinjuku to repel a vampire invasion where he was overcome in combat by Mikaela Hyakuya.

Guren is a tall, young man with medium length black hair similar to an overgrown wavy mullet, with slightly overgrown messy bangs parted in the middle and complementary violet purple eyes. He is considered quite handsome according to some girls who are infatuated with him. He is regularly seen in uniform based attire.