Despite his epithet, when he was younger, Zaine was very talkative. Always joking with his family, who descended from the ancient yakuza. However, one day, Zaine’s village was attacked. When this happened, Zaine was separated from the rest of his family and taken in as a slave by the Garaiyan empire. There, they trained Zaine to be a cold hearted killer, desensitizing him from good and bad, constantly drugging him with no regard for his well being, just focused on increasing their power. Zaine was the victim of an experimental drug which is injected directly into his heart and blood stream. This drug causes Zaine to temporarily gain a massive power boost however it makes him lose control and also causes him intense pain. Zaine does eventually escape from the Garaiyan empire, however the long term affects of this drug take their toll on his life and heart causing him health complications and loss of emotion over the course of his life. This makes him more silent, speaking only when it is absolutely necessary and also very stoic, making people call him the “heartless doctor.” The only two people who seem to somewhat understand Zaine on an emotional personal level are his brothers Damien and Roy. Roy acts as the intellectual brother that Zaine can share his critical thoughts and complex analyses of various characters with, whereas Damien is the brother who can support and stand next to Zaine in the heat of intense battle. To overcome his heart problems, Zaine performs a new surgery where he implants two extra hearts to support his main heart, giving him a total of 3 hearts, allowing him to pump blood much more efficiently and become much more powerful as well as unlocking a berserk mode where he uses all 3 hearts at the same time in combat, along with his dual katanas.
