His jokes lacked both delicacy or tact, and he was often told to keep his mouth shut.
After leaving college, he joined a major general contractor firm and lived alone till the age of 37, never having a girlfriend. Filial duty were left to his older brother, his life was essentially that of an independent, single noble. Neither short of height, or wanting of a good face; yet unpopular. He tried exerting effort into finding a girlfriend after confessing thrice. But after being dumped, his heart was left shattered.
He was stabbed protecting Tamura from a theft. Satoru’s “soul” linked with a spawned monster in another world. Into a dimensional crack so small that no eye could see. His soul linked with a mass of demonic energy. This mass was the origin of demons, and to Satoru who had linked to it, his thoughts as a base, the mass constructed a body. What is normally is essentially an impossibility with an astronomically small chance of occurrence, Satoru was reborn as a monster in another world.