Tsukasa Koudou

Tsukasa Kōdō (香道 司 Kōdō Tsukasa) is Yoite's younger half-brother. Although he was generally forbidden to approach Sora as a child, he still made contact on occasion, going to speak through the window of the basement to Sora, and at one point, leading him outside to play a game of catch. Their father threatened Tsukasa with a similar fate to Sora's, should they interact again, saying, "That's a ghost. If you interact with it again, I'll make sure you never existed, too!" Tsukasa was present during the attempt on Sora's life; he was told to participate as well, but refused. This allowed Sora's escape, and accounts for the fact that he lived through it. Tsukasa harbors a great amount of guilt for his inability to further help his half-sibling. After entering high school, the disagreement he held with his family was too much, and he moved away, on his own, to the town in which Sora's attempted murder had taken place. Later, he meets Kazuhiko Yukimi, and Yukimi becomes aware of the fact that Tsukasa is Yoite's brother. However, instead of relaying this to Tsukasa, Yukimi simply says that Sora is dead. After Yoite's erasure, Tsukasa keeps in contact with Yukimi (and then Miharu), sometimes visiting with Yukimi's cat, also christened Yoite. (Source: Wikipedia)