Naoto Watari's life has revolved around his little sister. He forgoes club activities for the sake of spending time with her, leading many of his peers to label him a siscon. But as long as his sister's happy, Nao is willing to shut out any unwelcome comments about himself.
Naoto Kuniyoshi is a bored, misanthropic youth who feels he was born in the wrong era, believing that he has more in common with the samurai and ninja of Japan's past than those living in the decadence of the present day. Having been nick-named "Ghost Boy" for his ability to go through life almost completely unnoticed by those around him, the twenty year-old student spends his days setting up spying equipment to stealthily take pictures of young women around his college campus, which he later photoshops into pornographic images for his "collection." Everything changes when Naoto is recruited by an enigmatic coordinator to participate in a special "tournament" with promises that he will lead the life of a billionaire should he win. The catch: to progress through each of tournament's 8 rounds, Naoto must find a way to kill his opponent using only indirect means, with all of Japan designated as their arena. After unwittingly agreeing to join the tournament, Naoto is immediately thrust into a world of murder, torture, and espionage that he never dreamed could exist in the modern day.
Hikari's roommate. She is a somewhat forceful girl who also seems to look out for Hikari, who she is in fact in love with. Yaya is good friends with Hikari though they've only known each other for about a year once the story begins. Yaya got Hikari to join the St. Spica Choir the previous year, most likely in an attempt to give her more self-esteem which she seems to be lacking in, though Hikari did show interest in singing as well. Yaya is one of the most talented members of the choir, as noted by Tsubomi Okuwaka, though seems to need more dedication, as noted by Hikari. She also has a rebellious side, sometimes going against school rules or what is normally accepted. However, when it comes to matters of love, she seems to be very shy about her feelings, substituing words with actions, sometimes with adverse results. Also, she rather dislikes first year students - such as Tsubomi Okuwaka - because they are noisy and annoying. (Source: Wikipedia)
Naoto is a member of the Crasher Squad.
One of the candidates for becoming an astronaut. Oldest member of Team A with a childhood dream of building Japan's first manned rocket. Had once a wife but they divorced because of Naoto's work. They have also one daughter.