Chihiro is very intelligent, but he also has a very meek and timid personality. He is very shy and apologizes a lot - it's easy to intimidate him to the point of tears. However, he also loves to talk about anything related to his work as a programmer and he becomes more lively whenever the topic is brought up.
Chihiro is one of the kindest and softest characters in Danganronpa, as he literally wouldn't hurt a mosquito, because it's "hungry and might have a family". After Leon Kuwata's execution, he felt guilt-ridden, even though it wasn't his fault. When he was attempting to reason with Byakuya Togami in Chapter 2, he revealed a deep disdain for disputes occurring between friends.
Unfortunately, Chihiro also had a deep-rooted complex over being looked down on by others as being "weak". This happened as a result of memories and experiences from his childhood where he was frequently bullied and told to act tougher due to him being rather frail for a boy. To make the bullying stop, he started disguising himself as a girl to avoid the pressure of having to become stronger. However, this only made his insecurities even worse. Though he tried to hide it, he gets uncomfortable when others treated him as a girl, and he would rather spend time with other boys instead of girls. He greatly admired men who are physically strong and he wished he could be like them.
When Monokuma threatened to reveal everyone's secrets, including Chihiro's real gender, Kiyotaka Ishimaru came up with the idea that everyone should share the secret right away. Naturally, most of them declined the request. However, Chihiro was one of the very few who planned to reveal his secret out of his own will. Instead of falling into despair, he became very determined to overcome his weakness and planned to become stronger so he could be his true self. Sadly, he didn't realize that he was already showing a significant amount of strength, due to his determination and will to confront his own core insecurities.
In school mode, Chihiro states that he enjoys reading and baking, but is afraid of earthquakes, big crowds and singing in front of other people. He really likes rabbits and hamsters and would like to have a one as a pet. He wonders if there are any in the school.
When Chihiro was a child, he was too weak to play outside with his friends, causing him to begin playing on the computer to make the time pass. His father, Taichi Fujisaki, was a software engineer that developed many major computer programs, and one day, Chihiro found an incomplete information retrieval system on his father's computer that utilized voice input. This led to him creating his own modifications for it, and he soon realized that he could write programs by himself.
Chihiro's father praised him for his work and, as he finally found something he could take pride in, he became absorbed in programming. He really wanted to help and be useful, but he thought he was useless without a computer. Chihiro's outstanding programming skills would later serve him in contributing to the creation of the Neo World Program.
Reason For Cross-Dressing
When Chihiro was a child, he became the subject of harassment and bullying. He was always told to "be a man" and that he was "so weak despite being a boy", and because of that, Chihiro slowly but surely began to develop a "weakness complex". In order to escape the bullying, Chihiro began to dress as a girl so that people wouldn't bully him as a weak boy. This only served to worsen his complex, as it wasn't addressing the root of his problems, and he would get bullied even more if the truth was found out.