Arata Kaizaki is a 28 year old male (27 in the beginning of the story) who is the second test subject of the ReLIFE program in Kanto and is under the watchful eye of Ryo Yoake, who is also under the ReLIFE drug.
Pre-ReLIFE- A young adult male with broad shoulders, dark hair and blue eyes.
Post-ReLIFE- His height remained the same, but his frame seemed to have gone away and his face took on much more of an adolescent look. His hair became shorter and his eyes remained the same.
He likes the act of helping others and caring for everyone. He has a strong sense of justice which is one of his strongest points, but is also a major flaw.
He describes himself as persevering and someone who would stick to something until the end once he has made up his mind.
Little is known about Kaizaki's childhood aside to the fact that he had his life planned out from the beginning. He planned to graduate, have a job, and get married at 25 (which sadly didn't come true, due to his being unable to get a girlfriend and becoming a NEET). His mother covers his living expenses until he was laid off (which eventually became one of the factors that led him to accept the experiment).
He used to work in a company that did a Flower Business under the leadership of his senpai. He was disappointed at the way the people in the company did their work wrongly and blamed it on her. He tried to fight for her sake which did not work as well as he planned. In the end his senior committed suicide, an event which traumatized Kaizaki. Afterwards, he tried to justify her death. which resulted in him being fired from the company, three months after his employment.
The event became a black stain in his life, as well as in his resume which hindered his chances of being employed in other companies, until he eventually turned into a NEET.
Arata is 27 year-old man, unemployed and forced to work odd jobs in order to get by due to his parents cutting him off. His life is changed when he met Ryo Yoake and was offered the chance to better his life. Ryo presented Arata with a card that read ReLIFE which is organization that helps people like him. He tells Arata that he would put through an experiment that'll last a year and if he performs well he might be offered a job at the organization. Excited, Arata takes up the opportunity as Ryo gives him a pill that would make him look like a 17 year old.
Michiru Saiki - Kaizaki's superior at his previous job. She was a victim of constant harassment by her colleagues, something that really bothered him.When Kaizaki tried to help her, the attacks became even worse and Saiki committed suicide. Arata blamed himself for her death and lost faith in society and in his own worth, leading to the events depicted in the story.
Chizuru Hishiro - He becomes her first friend. He thinks she's cute and is impressed she's trying her best to overcome difficulties in her life, unlike him. She initially gave him a little sister vibe, but in the recent chapters he's realized that he's in love with her. However he's unwilling to act, as he sees that playing around with the feelings of a young girl is unhealthy, as the memories will be erased at the end of a year. Kaizaki believes that is a very cruel and unethical thing to do. Currently he supports her as they go through the year keeping his feelings intact.
Rena Kariu - She lends him a pencil on his first day of school. He goes out of his way to help mend her relationship with Honoka and improve the relationship between her and Hishiro. He also was responsible for Ohga realizing his feelings for Kariu.
Kazuomi Ohga - Ohga was one of the few students to first interact with Kaizaki. Ohga helps Kaizaki prepare for his makeup tests after he fails them. Kaizaki is disappointed at the fact that Ohga is dense even though he is so handsome. Kaizaki makes him realize his love for Kariu and is responsible for him confessing to her.
- "There is no right answer for getting along. Different people require different answers."
- "Well, you don't have to rush things. You'll make friends in time. I'm sure."
- "Trying to knock others down a peg means lowering yourself. Don't go trampling all the hardwork and trust you've built up. It insults the effort you put in. The only way that would make you happy is if you were a loser who'd giving up on trying."
- "Please, let that iron guard down for a minute. It's only hurting you. I know when you"ve hit rock bottom, people trying to cheer you up can be really annoying. "What would you know?""Just leave me alone." But what if someone you're pushing away is really worried about you? That'd be a shame.
- “Thanks for thinking of me that way. That alone… makes me think this ReLife was worth living. Though you’ll forget me…”