Nakajima Arisa: A young orphaned medical student. Her mother had been the test for the anti-virus because of which she carries the immunity within her body. She is pursued by researchers and the virus infected people. Arisa is usually quiet and calm but when she is around Ryosuke, she is hyper and talkative. She had feelings for Ryosuke. She was brought up by Yuto’s family.

Yamada Ryosuke: The son of the police commissioner. His father is aware of Arisa’s role in the anti-virus and protects her from harm. He passed role to his son. Ryosuke is calm laidback and extremely flirtatious. He cares for Arisa and takes special enjoyment in teasing her. He fell in love with her when he met her the first time. He is aware who Arisa’s parents are.

Nakajima Yuto: Ryosuke’s childhood friend. Yuto’s father was the then head researcher of the virus and was against using Arisa’s mother as a subject as her blood rejected the virus. His father had rescued her mother and adopted Arisa the moment she was born. Yuto cares for Arisa as his own sister and is ready to fight for her.

Chinen Yuri: A researcher who comes across Arisa. At first he wants to do tests to Arisa to understand why she rejects the virus but decides to protect her. He is one of the youngest researchers who are aware of the anti-virus and who want to stop it's misuse. He lost his parents to the virus and wants to prevent others from going through the same.

The Organization: Nothing much is known about this but it is known that they want Arisa. They plan on conducting tests illegally on her to find a cure and then finish her off. They want to monopolize the cure for their greed. (The pic is just their symbol)

Valtore: He is the leader of the infected. He wants to spread the infection to the world. He wants to destroy Arisa as she carries the anti-virus.