Renji Magatsu is a childhood friend of Yuuya Daigo. He was a quiet, withdrawn, and sickly teenager, always being physically abused by his drunkard father. Renji grew strongly attached to "Yuu-chan" because Daigo was his complete opposite, strong both in body and mind, and yet understood him; sympathetic Yuuya was always willing to listen and support Renji.

Renji Magatsu became a member of the Twelve Generals, and as the Martial Fist was set to assassinate the Magami Five, he naturally went against Yuuya Daigo, drawing his old friend back to the place they used to hang out. With Renji calling him a traitor, Yuuya couldn't fight him, instead running away.