Rinji Amatori

"Osamu, I'm sending this message in advance, and if you're reading this, then it means I'm not coming back. I'm sorry I lied but I couldn't take you with me. You're just too sincere and honorable. Just please... stay by Chika's side."

- Rinji's final message to Osamu.

Rinji Amatori is Chika's older brother, and Osamu's former tutor.

Appearance
Rinji is a young man of average age. He has slick, neck-length light brown hair, and also black eyes.

Personality
He is quite caring about Chika, as he explained to Osamu the pain Chika went through after losing her friend.He doesn't seem to trust Border, for unknown reasons. He also seems to trust Osamu a lot, as he told him to take care of Chika should anything happen to him. However, later on, Chika describes him as an initiator, doing what he must if he wanted something.

History
Rinji was Osamu's tutor. Months before the start of the story, he told him Chika's backstory regarding her friend's disappearance. He told Osamu that, if something was to happen to him, he should protect Chika, which was the reason why Osamu joined Border. On April 28, he revealed his mission to try to go to the Neighborhood, and on May 2, he was declared to be missing. He was suspected to have collaborated with Mirai Hatohara, who had stolen Triggers from Border.