Coming back to this topic cause I just remembered something...
Sennin wrote:6. No Honorific (to people you hate, very young children, or when addressing a very rude person like Inuyasha who doesn't add honorifics to anyone's name)
Well, Inuyasha is sometimes called "sama" by those that are his "underlings" like Myoga-jiji ("jiji" meaning "old man BTW).
But also, in some show like taking Fruits basket for example, if you just call a person by their name it's a rather, good sign. When Tohru stoped saying "Sohma-kun" and called Yuki by only his first name, it was a sign of extreme closeness. On another ep, the Yuki fan club girls have a little speech on who calls him what. So roughly they were saying "lower classmates called him "Yuki-sempai" classmates his age call him "Yuki-kun" and upperclassmates call him "Yuki"". Something along those lines^^