Ryuunosuke Nagumo

The twin brother of Hizuru Minamikata. Ryuunosuke was killed by the shadows in middle school.

Though he was killed by Haine, he was also copied and his shadow went into Hizuru, thus forming a bond that let the two switch places in taking control of her body. He often takes control whenever shadows are around, so he dirties his own hands so his sister doesn't have to. The reason for Ryuunosuke seeing two seconds ahead is due to Haine's human-side splitting from her main self with an error of 2 seconds ahead in time, which led to him not just seeing the future but fighting in the future. He often has to hold back when fighting to not damage his sister's body. After Hizuru is killed, Ryuunosuke is transferred into Shinpei's mind. From there, he helps protect Shinpei and fights for him.

When they enter the shadow world, he takes full control of Shinpei's body and keeps him safe from dissolving. While he talks to Shinpei, he wishes to be casual and stops hiding his accent. This makes Shinpei casual with him. In the end, Ryuunosuke is alive and an adult with a reincarnated version of Haine as his daughter.