Reiraku

are the visualization of Reiryoku into threads which a spiritually aware person can follow. According to Rukia Kuchiki, this is a high-level technique. To the user of the technique, a Shinigami's spirit thread appears to be red, while that of other beings appear to be white. Ichigo Kurosaki was able to see spirit threads for the first time when searching for a Plus hiding inside a pet bird, and later when he had to journey to his "inner world" (the depths of his soul) in order to learn the name of his Zanpakutō.