It was later revealed in the series that Abe no Yauaki is actually an artificial human created by the famous sorcerer, Abe no Seimei, by combining his “yin” to his wife’s “yang”. As such, there was something lacking in Yasuaki, and Seimei placed a charm on his face to compensate for this. Because he lacks emotions of his own, he is highly sensitive to the Priestess Akane’s thoughts and emotional state. On one occasion, Yasuaki shed tears with a blank face when Akane became very upset.
Japanese cosplayer Ichiha (イチハ) makes a lovely Yasuaki, don’t you you think? I managed to find most of the books from this series, I’m just lacking the earlier volumes now! But I really love the artwork on the manga. Maybe I should pick up the anime too.
Source: イチハ on Cosplayers’ Archive