I feel something wrong when thinking about it.
Japanese is the country of “ Last name culture”, they usually will not use the first name to call each other. Follow my knowledge, they only use their first name to call someone if they are members of the same family, or if they have a very close relationship with each other.
However, in FSN, characters usually call each other by their first name. And I can’t understand their logic.
1/ Begin with Shirou. He always calls Shinji, Sakura, Issei by their first name. However, he always calls Rin is Tohsaka, even after they have sex with each other in UBW route.
I can understand that he has a close relationship with Shinji, Issei, and Sakura.
So, what is Shirou’s logic here? He thinks Issei and Shinji are more close to him than even his lover ( Rin in UBW route)??
2/ Next is Rin. She always calls Sakura, Kirei by their first name. She usually calls Shinji by his first name,too. And she calls Shirou by his first name from day 4, just several hours after he accepted to fight in HGW, if he accepts to ally with her ( meanwhile, Shirou still calls her as Tohsaka).
I don’t sure whether Rin trying to show Sakura as her real sister or not ( when Sakura begins to call her as Nee-san, she feels confused and doesn't ready to accept that relationship). But I am sure that Rin always hates Kirei and tries to stay away from him. She doesn’t have a relationship with Shinji,too. But exclude the prologue ( call him Matou-kun while he tries to seduce her), she keeps calling him Shinji almost everytime, no matter he is her enemy.
Meanwhile, she still calls Ayako by her last name everytime. While Ayako is her only close friend before when she knows about Shirou.
So, what is Rin’s logic? She calls anyone in the Magus’ community by their first name?
3/ I don’t know if I should include Illya here. She always calls Rin, Sakura, Shirou by their first name. We can say that Illya is a foreigner and doesn’t know about Japanese’s culture. However, Medea is a foreigner,too. And she calls Kuzuki by his first name ( Souchirou-sama).
4/ Meanwhile. Shinji and Issei always call Shirou by his last name ( Emiya), while Shirou always calls them by their first name. Isn’t it so strange?
So. All of these points have any meaning and logic? What Nasu trying to say? Did I miss something here?