• "Ri" (莉) means "jasmine" and "ku" (玖) means beautiful black stone. Riku's birth name literally translates to beautiful black jasmine or beautiful black jasmine stone. In most civilization, the color white is associated with the jasmine flower. But as it is black, the flower has been tainted. In Taoism, it is a symbol of feminity and purity.
• Prior to their arrival to Edo, both Rika and Riku mostly kept to themselves in Horai. The only other Tensen he showed close companionship with is with Gui Fa.
• Rika and Riku are based off of the Taoist Immortals He-He Er Xian. They are popularly associated with happy marriages. Something that Riku deems he need not because the only love he will recognize is the familial love which is with Rika.
• Despite his lean and muscular built, his incredibly pretty and feminine face contrasts sharply. Often times at work, the others at the Yamada school would take a peak outside the wooden sliding door just to see Riku. When the male would turn his head towards their direction, they would immediately hide back.
• Ever since Rika entered the Yamada school for the first time, Tenza and Kisho kept asking him for details about her.