Yu Kirasawa (吉良沢 優 Kirasawa Yū), also known as Illustrator (イラストレーター Irasutorētā), is one of the major characters of Ultraman Nexus and the strategist of TLT. Like Ren, he is also a Prometheus Child.
Yu was also one of the Prometheus Children, going through a similar lifestyle like the others. He also attended the institute of Dallas and meet Ren, both of them seemingly becoming close to each other. While Ren escaped from the institute to lead a "normal" life in Japan, Yu continued his education at the institute and eventually deployed in TLT Japan.
As the TLT's strategist, Yu usually coordinates the Night Raiders' operations against the Space Beasts as part of the CIC (Combat Information Center). Appearing in the form of a hologram, he knows more about the Space Beasts and Nexus than he seems to.
Meeting with Ren again
"Ren, can you hear me? Ren, believe in the light!"
- ―Yu encourages Ren when fighting Izmael
After seeing Nexus Junis Blue debut, Yu was contacted telepathy by Ren, who wants Yu to record his battles as Nexus. At episode 36, Yu contacts Ren that a cure has been made for him. However, Ren chooses to defeat Izmael and during the battle, Yu encourages a weakened Ren/Nexus to believe in the light, allowing Ren to finish off the Space Beast.
In the finale, Yu was the first one to confront Ishibori (Dark Zagi) at Floor O, Yu was eventually joined by the other Night Raiders. However, their efforts were in vains and warned Nagi not to transform but she did not care and become Nexus only to allow Zagi to restore his original form and later witness Komon dashing to the darkness to save Nagi and destroying Lethe in the process. Yu later watched the fight between Nexus/Noa (Komon) fight with Dark Zagi.