For anyone who is confused here. Shu and Yuma used to be bestfriends when they were kids but then reiji burnt yuma’s villiage (back then he was called edgar) so shu thought edgar died in that fire. But he didn’t instead he turned into a vampire as u can see but he lost all his previous memories. So yuma doesn’t remember being friends with shu at all . But shu, as you can see seems to be realising the fact that Yuma is Edgar.
you have heard about Edgar in the Anime? that was Yuma. He "died" in a fire, because Reiji set the whole village on fire. since that day Shu is afraid of fire. as you can see, Yuma"s a vampire now, i cant remember how. maybe it was explained in the anine. But Yuma lost his memories about the time Shu and Yuma were friends. i hope you understand and sorry for my bad english, cause im from germany😅