He has one special power in particular: to create a poison cocoon which was used to seal InuYasha in before his demon blood took over and he was able to slash the cocoon open and defeat Gatenmaru.
InuYasha also later faces Gatenmaru's brother, who instead of using poison cocoons as an attack, instead encases the victims and attacks them in their dreams.
Gatenmaru scoffs, and transforms into his true form, a giant blue moth demon, but he underestimates Inuyasha and is quickly ripped apart.
Inuyasha also later faces Gatenmaru's brother, Gamamaru, who instead of using poison cocoons as an attack, instead encases the victims and attacks them in their dreams.
Gatenmaru's henchmen don't know that he is a youkai until he traps Inuyasha and Miroku into a cocoon and then drains one of the captured women of all her blood.
Elsewhere, Inuyasha and the others arrive at a village that is ruthlessly being held under the control of the Moth Demon, Gatenmaru and his band of thieves.
This episode is based on the events from the end of chapter 181-the beginning of 185 in volume 19 of the manga.
Boku'seno reveals that the sheaths or scabbards of Tetsusaiga and Tenseiga were carved from his branches, which explains some of the mystical power contained in the simple looking wood.
