He became the Student Council President after Kanade got demoted, though becomes the Vice Student Council President again after Kanade is given her status as the Student Council President back.
Naoi was the son of a famous potter. He had always lived in the shadow of his talented older brother, who was named heir to their family at a young age. Naoi spent most of his time isolated in his room, until his brother died in an accident. After his brother's death, Naoi was told that "It was you who died," and thus he took on the role of his brother, undergoing strict training in order to live up to his brother's standards. Naoi, however, could not compare to his brother, but he worked hard and eventually won an award. He believed that he would continue to work with his father and eventually become the best potter in Japan. However, his father was bedridden, and Naoi was forced to tend to his Father, and so was not able to continue working. Naoi believed that his life was meaningless because he was always living for either his father or his brother.
Naoi then "joins" the Battlefront and still acts as the School Vice President. He seems to greatly admire Otonashi, and always listens to him, giving Otonashi the "Older Brother" role to Naoi. Naoi also seems to be younger than Otonashi and Yuri, which makes him an underclassman like Yui. He refers to Otonashi as "Otonashi-san" and the rest of the Battlefront he usually refers to them as "You" and "Them", showing respect to Otonashi but disrespect to the others.