Episode 21 (Hanyō no Yashahime)

"Secret of the Rainbow Pearls" is the twenty-first episode of Hanyō no Yashahime.

Summary
Kaede tells Towa the story about how their young teenage human mother, Rin, had mysteriously disappeared after giving birth to them fourteen years prior. While reflecting, Towa, who has been affected by the new moon again, is approached by Riku. He tells her the story of the demon female who had looked after him many, many years ago and how the seven Rainbow Pearls were created after her grandfather Tōga's demise a couple centuries ago. Riku finally puts his plan into action by luring Towa into a trap. Distracted, a defenseless Towa is attacked by Tōtetsu, which Riku does not take kindly.

Plot
223 years ago, amidst the news of Tōga's demise, a saddened Zero decides to use the Shikon Jewel to seal her emotions, which creates the seven Rainbow Pearls. Back to the present, its the new moon and with Towa's power diminished, Setsuna orders her to take shelter at Kaede's home. In the occasion, Kaede reveals to Towa that she lived many years with Rin until her disappearance that occurred just after she gave birth to the twins. Seeing a Dream Butterfly passing nearby, Towa chases after it all the way to the Sacred Tree of Ages, until she saw the fireflies and follows them to spot where she meets Riku.

Riku reveals that he intends to gather all Rainbow Pearls and return Zero's lost emotions when Tōtetsu appears to attack her. Riku risks his life to defend her until Setsuna and Moroha arrive to help them. Riku takes the opportunity to slay Tōtetsu and Towa gives the Rainbow Pearl in her possession to him to help with his mission, but she regrets soon after when Setsuna points out that Riku's master could use them for evil ends.

Trivia

 * Towa confirms that it's currently winter. Though unlike winter in the modern era, the weather is only mildly cold as Towa doesn't feel cold in her human form until a breeze strikes.
 * This marks the second time Towa becomes full human.
 * Towa learns from Kaede that her mother's name is Rin.
 * Tōtetsu being weakened by miasma bees of the dead summoned by Riku while using his air breath is similar to Miroku being weakened by the Saimyōshō of Hell while using his Wind Tunnel.
 * As of this episode, all the Four Perils have been slain.
 * Towa gives her Rainbow Pearl to Riku.
 * This is the first time that the Sacred Jewel is shown via through a flashback around the time that Inuyasha was born, as well as Tōga's death.
 * Tōkotsu is the only Shikyō to not appear in this episode at all.
 * It's been revealed that Riku is only doll since he was around the era of the Great Dog General's reign.
 * Kaede confirms Rin disappeared shortly after giving birth to the twins.

Error

 * Tōga is said to have sustained grave injuries from battling Shishinki and Ryūkotsusei, although Tōga had fought Shishinki and stolen his technique before he and Kirinmaru destroyed the Grim Comet 500 years ago as he was using an incomplete Meidō Zangetsuha. Unless Tōga fought Shishinki again.