InuYasha Episode 58: Fateful Night in Togenkyo, Part II
Episode 58 of 167 of InuYasha, aired January 28, 2002, 24 minutes. Available with English subtitles and dub where released.
Episode summary
After Sango leaves to repair her damaged Hiraikotsu, Inuyasha and the others come across a Demon tree and the Peach Man who uses humans to feed it so it can grow a fruit of immortality. Not only do the four manage to caught by the Peach Man in some way, but it's also the night of the New Moon when Inuyasha becomes human!