Shion will have on him his regular clothing and a long red toggle coat under which is a sweater. Additionally he'll be accompanied by a tiny black mouse robot named Tsukiyo (Moonlight). The robot is able to understand human speech, carry messages, and project small holograms if it is given the data one wants to project. Holograms are a piece of technology from his world though, so he won't be able to get new data onto Tsukiyo for projection right away. Tsukiyo also has a bit of personality, and he seems to have affection for people who are nice to him. He was a gift to Shion from his friend Nezumi.

Imagine a bright, pleasant, polite young man who is poised to accomplish great things: Shion is the perfect picture of such a prized model citizen. At least he is at first, until the glamour breaks, and his actual humanity comes rushing in.

In general, Shion really is a pleasant and bright person. He has a very, very high IQ and has a set of manners which six months of living in abject poverty has not eroded. He does not hesitate to help children who come to him hurt and is rather fond of animals of all kinds—even rodents. In fact usually has an easy rapport with animals and quickly gains their trust, loyalty, and affection. When he sees people whom he perceives as weaker than him, it stirs within him a protective instinct which spurs him to help them without thinking about the consequences. At least it does when his empathy and sympathy aren't being overloaded: if he sees a mountain of corpses and the half-dead, he's not going to be able to help them at all and will actually need some help himself to pull it together. If there is a single dying man who is begging to be put out his misery, Shion will help him, even if he can't manage to strangle the man himself (and actually causes the man more pain trying to help him.)

Which is to say that Shion cares. He really, truly does. Even though he admits to himself that he does not think he is any saint and wouldn't help just anyone who came to him in need, and he says that he does not particularly like people, he actually does extend a hand to those who need it. Such behaviour brought him into contact with Nezumi, his closest friend and partner.

On his 12th birthday there was a typhoon. Not a big deal for such a technologically advanced city as No. 6, but it was a big deal for Shion. The wind and rain and noise excited him, to the point where he experienced a purely destructive impulse for the first time. He did not have time to dwell on it, however, as he had an urge to throw open his window and yell. By doing this he left himself open: and in slipped Nezumi, a twelve year old too, but a twelve year old who was bleeding, aggressive, and on the run. When Nezumi grabbed at Shion's throat, Shion didn't think to panic, however, instead he was focussed on helping Nezumi.

Shion helped Nezumi primarily by performing basic surgery to close the gunshot wound on his shoulder. (Yes, Shion could perform basic suturing at the age of twelve. It was partially his general education, partially his crazy mental proficiency.) Afterwards he gave Nezumi food and allowed him to stay in his room although he knew that, by sheltering Nezumi, he would lose all of his privileges granted to him by No. 6 because of his status as an Elite. Shion does all of this for this boy without any thoughts for what he would get out of it. And, after he does lose all of his privileges and has to move a poorer part of town, Shion tells himself that he doesn't regret it, he wouldn't have made a different decision if he had the chance. Shion isn't one to hold grudges: he means what he does and accepts the consequences for his actions.

His ability to not hold lingering grudges is also evident in his relationship with Rikiga. At one point Rikiga and Nezumi start bickering, to the point where Rikiga basically tells Nezumi that he should become a prostitute. Shion, sitting right by Nezumi, becomes so upset that he cries and physically assaults Rikiga. In the end Rikigia becomes something of a father figure for Shion. And Shion, despite Rikiga still arguing with Nezumi, drinking, and printing a pornographic magazine, is able to have an amiable relationship with Rikiga. He maintains it even when Rikiga basically says that he wants to get with Shion's mother. And, whenever Nezumi is bluntly honest and calls Rikiga a fat old alcoholic, Shion tells him off.

Although he has a massive mental intellect, Shion is not exactly the best problem solver. He is good on a theoretical level given that he possesses as much knowledge as he does. He is also good at logical thinking in that he can come up with a range of possibilities and game out scenarios. What his problem is, is that he is overly emotional. He doesn't want anyone to get hurt, and he is emotionally invested in finding the most ideal solution. Shion often advocates for a less violent way when Nezumi goes on about his hatred for No. 6 and his desire to destroy the city. He inspires Nezumi to consider that there might actually be such an option. He is able to give Nezumi hope that there might be one.

While inspiring hope in others is a vital quality for a leader, Shion does not possess many of the salient qualities desirable in a leader, at least not naturally. He is not able to make purely rational and logical decisions because of his emotions. Nor is he able to handle stress very well. He can at least admit when he's wrong, and he's earnest, but those aren't qualities which are particularly attractive in politicians.

Another one of Shion's flaws is his fatal clueless. Partially this comes from living such a sheltered and privileged life. Nezumi comments on it several times, saying that Shion is a burden because he is so utterly unable to take care of himself. Inukashi also comments on Shion and finds it hilarious that Nezumi would keep such a useless pet. On the other hand, though, a good deal of his cluelessness just seems to be a general part of his personality. He spaces out when he's thinking, to the point that he misses entire parts of conversations that are going on around him. He is also unable to recognise when someone is flirting with him. At one point an older woman with a food stall gives him free high quality cheese and calls him handsome. He thanks her, and then leaves, and later on that evening Nezumi gives him a hard time for not taking advantage of the situation. He tells Shion that he could have gotten a more if he had played along which comes as a surprise to Shion.

And, most cringe-worthy of all, is the fact that Shion doesn't realise that his best friend of many years, Safu, has a sexual interest in him. It isn't until she comes right out and asks him to have sex with him before she leaves to study abroad that he realises there was any sexual tension between them. He turns her down, of course, but he then attempts to ameliorate the situation by telling her he'll have sex with her when she returns in two years even though he obviously doesn't have any interest in it. To rub it in he ditches Safu about three seconds later when he thinks he might have found something connected to Nezumi after they've been apart for four years.

Another thing about Shion is that he is called angelic by at least two of his friends, Inukashi and Rikiga. The thing about angels, though, is that their original nature is often overlooked. Angels—in the Biblical Old Testament sense—are not kind and caring beings. Rather they are intermediates between humans and the Divine. They are designed for a function, and they have a form, but they don't have feelings. So, when they call him angelic, they mean it as a compliment, but it displays a fundamental misunderstanding.

There is a dark side to Shion that few know about. Only Nezumi has witnessed it, though Inukashi has sensed it. This dark side surfaces when he's triggered. What triggers him is primarily seeing those he cares about come to harm. He switches when Nezumi is in danger of dying twice, and he switches once when he blames Nezumi for the death of his childhood friend Safu. When he has switched, Shion is ruthless. His eyes go blank, his expression freezes, he becomes calm, and he becomes capable of acts that he is not when he is normal: namely, killing.

There is definitely some disconnect when he's in this state. He doesn't remember what he's done when he's back to normal. This is evident when he freaks out when he realises he has killed someone by shooting him. The killing really was brutal, too, as he shot the man point blank in the head. Of course the man had shot Nezumi and was going to going to shot both Nezumi and Shion to death, but still. This kind of act is so utterly uncharacteristic of how Shion normally is that it can only be explained by a complete switch of personality. He is made uneasy by this side of himself, too, so it's not something that he accepts or will settle for. It's something that he will struggle against until he defeats it.

It has to be noted that this side of his exists because it is an important issue. Nezumi tells Shion directly that it scares him. At one point Nezumi said that he didn't trust Shion because he was so willing to renounce No.6 and claim that he wanted nothing to do with it, but that is mostly a separate issue. Nezumi is scared of Shion because he doesn't think that he can predict what Shion can do. This side of Shion scares Shion too. It's apparently not something that he can control, and though he does not remember what he did, he is aware after the switch that he was not himself for a time. The third time the switch occurs he cries and apologises to Nezumi since he realises he must have been away from himself. Nezumi forgives him, he understands why Shion was so distraught about Safu, but it is still something that makes Shion a black sheep, at least until he learns how to control his swings, if he even can.

For as amiable as he can be, it's hard to say that Shion has a good sense of humour. Telling jokes is an important skill for socialising. It is, however, not a skill that Shion has. To be sure he can manage comebacks, sarcasm, and irony. After spending time with Nezumi he's learnt how to deal with the insouciance and blatant prodding Nezumi can engage in when he's in a grouchy mood. One of the ways in which Shion deals is by being sarcastic back to Nezumi,. Another way he deals is by punching Nezumi back. He doesn't punch Nezumi without a reason, though! It's more a case that he's expressing himself in a way that's equal to how Nezumi has expressed himself. If he doesn't have the skill of joke-telling, Shion makes up it for understanding when he has to change his method of communication.

Seriously, Shion isn't sadistic. The reality he has come to inhabit outside of No.6 is violent and there's no way that a person who wants to survive can't be affected by it. And, for the destructive impulses that he has, and the murder that he intensely regrets, Shion is generally a pacifistic-ish person who does not enjoy violence or conflict. In fact he goes out of his way to avoid conflict. He admits as much early on in the series.

But, as non-confrontational as Shion is by nature, he is not averse to facing horrible situations for the sake of others, and this speaks to his sense of morality, his sense of responsibility, and his loyalty to others. He refuses to give up the memories of his mother when he runs from No. 6 and figures he will probably never see her again. He does not give up on the citizens of No. 6 even though they are complicit in the abuses the people outside of the city face; he does not condemn them. Shion honestly believes that they can come to some understanding of what is going on and work towards creating a fair and equal society. Nor does he give up on Safu after she's been kidnapped, going as far as to going up directly against the government. Shion ultimately allows his other friends in the matter and (although not at first, Nezumi has to convince him to), working together with Nezumi, he directly risks his life in order to save her. When he learns that he's failed, it utterly devastates him, to the point that he becomes suicidal. Nezumi has to pull him out of an exploding room.

Overall, Shion is in general a rather smart, though simplistic kind of person who means well and isn't afraid to fight for what he believes in, if he's really convicted. His conviction might come from guilt, but guilt isn't always a bad thing. And, speaking of being simple, he does enjoy simple pleasures. It's remarked upon in canon that he is good with his hands doing things such as making clay models or doing crafts. He enjoys doing physical labour with his body, likes to organise things, and finds it rewarding to help others if they are injured.

As far as motivations go, Shion is driven mainly by his relationships with others. A good example of this is his extreme personality change when the people he cares most about are hurt: he becomes a man of action, so to speak, when Nezumi is threatened in any way. He also turns on Nezumi when he thinks that Nezumi has allowed Safu to die. Of course it helps his drive when he actually cares about another person, or if he thinks that the other person is in need. Earlier in the novels he tries to help more people than he realistically can. He becomes easily drawn into others' conflicts; he almost gets saddled with a taking care of disposing a dead body, and he is almost gets shot when he stops a storekeeper from shooting randomly into a crowd to stop a thief.

He has come to learn to more sparingly involve himself; technically, at least, since he knows to game out an emotional situation a bit more before engaging in it, but good judgement is hard to learn. What it really takes for him to become reluctant with involving himself is if he faces a truly overwhelming situation. As mentioned before, he has a hard time of it when he's facing down a mountain of dead and dying persons, he just doesn't have it in him to stop and help them. Instead he joins Nezumi in climbing up the mountain of persons to get out of the pit they've all been dumped into.

A part of motivation from relationships comes from the promises he has made people. He has promised Nezumi that he will continue to live on, so he will do so at any cost. He has also promised Safu to carry on her dreams, so continuing on into the future isn't something that he can't not do.