In Shu's route of More,Blood (fandisc game), it is revealed that Yuma is actually Shu's childhood friend, Edgar. They met in the forest when they were children. Shu would often run away from home to play with Edgar and do various things like hunting and firewood collecting. Reiji soon became aware of the situation and set out to hurt Shu and impress his mother, by setting Edgar's village on fire. Edgar went into the fire, despite Shu's warnings that he'll die, in order to save his parents. After that, he never returned and all that remained were the ashes of the village.
Before the tragedy, some of their encounters included various things like - one time, Shu invited Edgar to come to his mansion during a ball and even gave him clothes to wear so he could fit in. However, during the party, Edgar was provoked by others including Reiji since he didn't know any etiquette nor how to dance, resulting him running out of the party embarrassed. Shu met up with him later on in the forest and Edgar returned the clothes. Shu noticed a scar on Edgar's shoulder, which is brought up again on the school rooftop as a way of confirming Yuma's identity.
In Yuma's route in More,Blood, he has a dream where he catches a glimpse of Shu, claiming they were friends. Confused, Yuma takes the heroine and ventures off to the Sakamaki's house. However, everyone was asleep, except Reiji. Reiji tells them to come back another time or to meet up with Shu at school, but Reiji suddenly realizes Yuma's identity. In Yuma's Manservant end, while at school, Reiji runs into the heroine and Yuma in the hallway and tells Yuma that Shu had caused the fire.
In Dark Fate (fandisc) Yuma's route reveals a lot about his lost memories he slowly regains, some of which are about Shu.
Driven by the persistently returning memories that torture Yuma he runs from the Mukami side of the castle in the demon world,and finds the old underground passageway between the demon world and his village where he sees Shu's true vampire name written, remembering that moment when they were kids. Yuma can't read it because he can't read the ancient vampire language but later when he encounters Reiji there, he recognizes it is Shu's true vampire name "Ririe".
Most of Yuma's memories slowly return, but the cause of that fire that killed his parents remains a mystery and he decides to confront Shu directly about it. After a long discussion with the heroine Yuma promises to not do anything rush,he simply wants to find out the truth because he wants to put an end of the past and move forwards in the present. Shu tries to take the blame, but this time explains the full situation that Reiji was the physical culprit but Shu believes is his fault instead Reiji's .Yuma gets confused but decides to let it be for now.
Depending on the ending Reiji can get mad at Shu for taking the blame and not acknowledging him even in his crime, but the thing with Yuma usually helps Reiji and Shu fix their own issues.
However, again depending on the ending, the First Bloods may kill them afterwords.
