NNT complete book:Neku's personality is rather unsociable. He has a lot of difficulty understanding people, so he always keeps to himself. Unfortunately, this results in his dislike of dealing with other people. His opinion of others is so low that he tends to see people only for their use. Neku refuses company, as he feels that friends only drag him down, cause him pain when they fail him and make him feel like "unnecessary baggage" to them. To him, society is simply an annoyance that forces their values on him, pester him and expect him to do things he doesn't want to do. As such, he admires the designer CAT for his/her "do what you want, when you want, where you want" motto.

Though at first his negative world view keeps his …friends alienated despite their best efforts, Neku slowly softens as he listens to the advice of everybody around him. He becomes more open and trustful of others as he gets to know people like Shiki, Joshua, Beat, Rhyme, Hanekoma and others like sora from kingdom hearts. As time passes, he begins to understand more about others and believes in his friends.

In the parallel universe of "Another Day(neku's new day)", Neku did have one friend, a classmate of his. However, this friend was killed in a car accident en route to meet Neku at Udagawa. Neku blamed himself for his friend's death, as he was the one who asked to meet. While it is not stated that the "main" Neku had this experience, the Secret Report for Book 2, chap 1 notes that Neku has had some sort of "trauma" in his past. Additionally, when Rhyme is erased, Neku says,"I feel like crap. This is just like that time.", supporting the notion that he has experienced the death of someone close to him. He constantly feels that he's becoming emotionally injured in this chapter