Basics
Arima is the product of a broken home. His parents were abusive and eventually dissappeared leaving him in the care of his foster parents. He works hard to please his new parents as much as possible, and attempts to protect himself from the abuse of his family by appearing to be perfect. In general Arima is a kind soul who always does his best not to dissappoint. He is highly self-conscious despite his outward appearances and is easily hurt. Rather than voicing any fears he may have, he tends to bottle them up inside until he can no longer contain them.

Innumerable Sides
At school, Arima is without a doubt the most popular man on campus. He's perfect on the surface: polite, smart, genorous, helpful and comes from a rich family. Essentially he is one of the school's elite members. However, this glossy exterior hides a frightened, self conscious little boy. Arima knows very little about friendship. True, he is friendly and gets along well with almost anyone, but he isn't really *friends* with most of them. He hides his true self and expends more energy than he realises in the process. In fact, for a long time, Arima keeps his mask up so well that it doesn't slip, even at home. Even his foster parents are subjected to the facade. It takes a massive punch from Yukino and an inspiring speech before he realises that hiding his true nature is something he must learn not to do. However, even after deciding to drop his mask Arima still carries it to a certain extent and is not completely true to his feelings.

Arima's reasons for holding up his facade are very important to understanding him. It all appears to stem from the abuse (both verbal and physical) that he suffered at the hands of his parents, as well as the onslaught of verbal abuse he is subjected to by a majority of the Arima family. He suffers from depression at times and has a serious lack of self confidence. He is in constant need of reassurance. Arima feels that he must be absolutely perfect for his foster parents and show that he will not become abusive like his father. The Arima family is high profile and they see his father as a discrace.

Despite Yukino's words and the knowledge that he must drop the facade, Arima continues to (perhaps unconsciously) carry part of it. Occasionally it slips, for example in book 6 of the manga (episode 17 in the anime) when Yukino shys away from his touch. Afraid of rejection Arima runs after Yukino and instead of simply talking to her when he catches up he grabs her by the arm, throws her against the wall and proceeds to shout at her, saying she can't leave him. Another such example occured near the end of book 7 when he was jealous of Tonami. Although Arima did not use any physical violence on him, he gave a look which could only be described as murderous and would have caused anyone to run screaming into the night.

Compared to Yukino's somewhat superficial reasons for keeping up her charade, Arima's reasons strike the heart of his emotional and possible mental well being. His mask is an attempt to protect himself from all his fears and insecurities. It will take him a much longer time to learn to show his true self.

Conviction
It is possible that a number of people will think that I have portrayed the poor boy in a rather negative light, but this is how I see him. In fact, the inner turmoil he faces is what makes him, for me, the most interesting character in the cast of Karekano. To me, Arima is a very fragile character, not physically, but most certainly mentally. His sudden mood changes (the incident with Tonami comes to mind) towards anyone but his family and Yukino are evidence enough of the possibility that he could snap at any time. This does not mean though that I don't think he's a nice person. The real Arima buried deep down inside is no meaner than any other person. He is at heart a gentle soul who fears rejection, but bottling up all his less acceptable emotions has led to the genesis of a rather two sided person. On the once side he is the kind caring and polite person everyone knows. On the other he is a jeaolous and possibly violent individual. Arima need to learn to merge these two personalities before he can achieve the balance he needs to become the person he wishes to be. Not the perfect model son, not the top student ; but the real Arima. One who can freely express how he feels and no longer fears a past which can no longer harm him.