is bleach episode 138 filler?

In Las Noches in Hueco Mundo, Ulquiorra Cifer and Yammy Llargo walk down a long hall and reach a large door, where Ulquiorra announces his arrival. As the doors open automatically, Sousuke Aizen welcomes them both and promises that this will not take much longer as he stands before a mummified individual with Coyote Starrk, Tier Harribel, Nnoitra Gilga, Luppi Antenor, Grimmjow Jaegerjaquez, and Aaroniero Arruruerie observing.

With Aizen dropping the Hōgyoku into a glass container in front of the individual, Ulquiorra asks him about its awakening status, which leads Aizen to confirm that it is only half-awake and will completely awaken exactly when Soul Society expects it to.