Battle Royale

Osamu Kasai (葛西 治虫, Kasai Osamu) is a minor character in Battle Royale II: Requiem.


Osamu was part of the Literature Club. He transferred to Shikanotoride to bring his grades up, but it didn't work out. He was well-liked by his classmates, but was shown to be timid and shy.

Friends and Enemies[]

He had a crush on Kyoko Kakei. He was possibly on good terms with Masami Shibaki and Takuma Aoi, since they were battling the ATAT Soldiers.

Before the Program[]

During the Program[]

During the initial landing, Osamu vomits in panic and follows his partner in a frightened and cowardly manner. During Mission 2: Securing Ammo he opens a crate containing toilet paper, which he later uses to try and help treat Shugo Urabe. When the students breach the Wild Seven's base, he immediately surrenders to the terrorists. When the survivors are given a chance to escape, Osamu confesses his love for his partner, Kyoko, and asks her what he should do in the face of the coming ATAT invasion, to which she tells him to go and fight, inciting him to join Takuma and the Wild Seven in buying the others time. He sacrifices himself when he and Satoshi Imakire blow themselves up with a grenade launcher, taking many ATAT soldiers with them.


  • The name Osamu means "reign, subdue" (治) (osa) and "insect, temper" (虫) (mu)
  • Osamu's surname Kasai means "arrowroot" (葛) (ka) and "west" (西) (sai)