Ep. 155: Rukia fights back against Kaien, exposing his fear of sunlight and binding him with Kido.

155

Rukia continues to struggle against Kaien, and he begins to overpower her when he uses the shikai of his zanpakutou. When Kaien disarms her, Rukia attempts to use a kidou spell, and reveals in the process that Kaien is afraid of the sunlight. Armed with this knowledge, Rukia binds Kaien with kidou and blasts a hole in the wall. In the sunlight, Kaien's face melts away to reveal a glass case with two masks inside. The creature reintroduces himself as Aaroniero, and after moving out of the sunlight, assumes Kaien's appearance again. After informing Rukia that he absorbed Kaien's remains when he came to Hueco Mundo, Aaroniero releases his zanpakutou, transforming his lower body into a giant, octopus-like form. (Source: Wikipedia) Arrancar: The Fierce Fight arc: (4/16)