Daisuke Wakui (和久井 大輔, Wakui Daisuke) is a student of 9th Grade Class 3 in 1998 at Yomiyama North Middle School.

Daisuke is a pale young man with slightly above average height. He has short dark brown hair and closed eyes (they are shown to be black in Sphere Joint). As a high school student, he is only ever seen wearing the standard male uniform.

Daisuke is a quiet, shy boy with delicate health (being asthmatic), so most of the time he is seen being alone or very rarely with someone. Despite his respiratory condition, he was seen in PE class, jogging like the other boys, suggesting that his illness is not serious as long as he has his inhaler handy.

Quiet and shy, Daisuke wasn't a major fixture of Class 3-3. He was present on Kōichi Sakakibara's first day of school, but did not welcome his new classmate, though he did move out of the way so others could. In "Build Limbs", when Izumi began enforcing her new countermeasures, which involved ignoring Kōichi, he tried to ask Daisuke what was going on, but Daisuke was unable to tell his neighbor. He was present when Mr. Kubodera killed himself in the middle of class, but wasn't part of the group who fled right away; he was seen vomiting on the floor before he pulled himself together and walked out.

In "Glass Eye", Daisuke was one of the students who went on the class trip. During the first night's dinner, he had an asthma attack. The cartridge for his inhaler was depleted. Before this, an envelope containing an inhaler/cartridge was shown on the table, in the corner between Daisuke and Tomohiko. Mr. Chibiki asked if there was a spare cartridge, and Daisuke weakly shook his head no. Telephone service at the lodge was out and not yet repaired. Cellphones could get a tower, but service wouldn't go through. So Mr. Chibiki drove him down the mountain to a hospital.

In "Stand By Oneself", it was revealed that Daisuke had managed to survive the calamity, as he was shown at a hospital along with Matsuko, Yukito, Noboru, Yūya, Kōichi, and Manabu.