Despite the fact that she shows little emotion, she does care about her fellow 'ITEM' members and in particular, Shiage, whom she is in love with. Even with her friends she would normally behave quite cold and detached but not in a bad way, she has been described as "lethargic" instead of stern or aloof.
Whenever a character has been put in a ridiculous position she usually address him/her with encouraging lines such as "Don't worry. It's ok, I'll support you", though her courtesy and condescending behavior will probably have the opposite effect and would bring a heavy blow to whoever she was trying to cheer up.
It should be noted that Rikou as shown a selfless side of herself several times, in many opportunities she offers herself as a bait to lure out enemy while her friends escape regardless of her own physical state; in other times she refutes the possibility of being rescued from danger as the risk is too high, it is also partly because of that selflessness that Hamazura Shiage wants to "bring happiness" to Rikou if possible.
As of New Testament, Rikou has developed a very possessive personality towards Hamazura and reacts strongly towards any sign of unfaithful behavior, to the point where Hamazura described that attitude as "a dangerous light in her eyes". It should be noted that Rikou has shown jealousy even in situations where Hamazura himself refutes that nothing can possibly be happening (for example, when Fremea was innocently sleeping on Hamazura's lap).