Bokusenō

was a wise tree demon who was an old friend of the Great Dog Demon who gave Sesshōmaru information on Inuyasha's demon transformation. The scabbards of both Tessaiga and Tenseiga were carved from his boughs long ago. His face emerges from the surface of his trunk and he can grow arms from his trunk at will.

The Tenseiga is delivered to Sesshōmaru by Tōtōsai, who hangs the sword on Bokusenō with an attached note. Being used in this way causes Bokusenō some minor discomfort.

Sesshōmaru came to see him on Inuyasha's scent changing to of a full demon twice (when Naraku's third incarnation, Goshinki, broke the Tessaiga, and when Inuyasha lets go of the Tessaiga during a battle with Sessōmaru himself). Bokusenō tells Sesshōmaru that Inuyasha can never be a full fledged demon and explains that when Sesshōmaru is in battle, he remains calm, and doesn't lose control. When Inuyasha's life is on the line, however, his demon blood awakens his most basic survial instincts. As his demon instincts take over, Inuyasha's human soul becomes overpowered by his demon blood, and he turns into a ruthless beast. As Bokusenō said, "In further transformations, he would loose part of his human soul. He would not tell the difference between friend or foe. He would only know how to kill until he is destroyed." Sesshomaru understands why Inuyasha has the Tessaiga, and he goes to find Inuyasha to see if Bokuseno's words are true.