|Previous Affiliation||Aizen's Arrancar Army|
|Previous Occupation||Decima/Cero Espada|
|Base of Operations||Las Noches|
First Battle with BenEdit
When Ben Tennyson entered Las Noches and later ended up in Aizen's throne room with the Espada present, Yammy was dispatched to interrogate Ben. Thinking quickly, Ben activated the Ultimatrix and transformed into Humungousaur, much to the surprise of Yammy and everyone else in the room. The two then fought, with Humungousaur initially having the advantage until Yammy began firing Bala at him. Ben transformed into Ultimate Humungousaur and once again turned the tables in his favor. Angered, Yammy prepares to release his Zanpakuto until Aizen calls off the fight.
After Aizen tricks Ben into joining him by spinning a tale of lies about the Gotei 13 and himself, Yammy properly introduces himself to Ben, silently fuming that their fight was interrupted and making it clear that they would have a rematch. Like all the other Espada, Yammy witnessed Ben use Way Big to give Nnoitra Jiruga a savage beating in retaliation for attacking Tia Harribel's Fraccion, and was visibly amazed.
Sometime after Ben's arrival, Yammy was sent to Karakura Town, together with Ulquiorra Cifer, to "test" Ichigo Kurosaki. Yammy returned badly injured, but did not discuss what had happened in detail. Later, he participated in a second attack on Karakura Town, where he was forced to lie about the Gotei 13 to keep Ben from getting suspicious.
Second Battle with BenEdit
Ben ultimately turned against Aizen after learning the truth. After resting to strengthen himself, a larger Yammy attacked Ben and his friends while they were trying to rescue Orihime Inoue. Ben once again turned into Ultimate Humungousaur and the two fought while Ichigo fought Ulquiorra. During the battle, Yammy also nearly killed Loly Aivirrne for interrupting the fight (and also for being an annoyance). Ultimately, Ben defeated Yammy but did not kill him, so Yammy inevitably recovered somehow.
Third Battle with BenEdit
Yammy was ultimately killed "off-screen" by Byakuya and/or Kenpachi. Despite mutual antipathy, Ben mourns Yammy's death.