Once Stain killed Tenya's brother, Tensai, Tenya realized why Stain does what he does; killing the incompetent heroes, the heroes that don't deserve their title. Though Tenya was originally fed up with Stain for killing his brother, he soon came to terms with the fact that his family was, in fact, not worthy of the "hero" title. Thus, led him to believe that he should follow in Stain's footsteps, following the path of a villain, since he failed at becoming a hero.