The One Left Behind (遺されるもの,Nokosa reru mono?) is the twenty-first episode of CROSS ANGE Rondo of Angel and Dragon, it aired in Japan on February 28, 2015.
When Tusk says he will push into the center of Misurugi Empire, Hilda lets out a surprised cry. On the deck of Aurora, Hilda gives an order to her Para-mail squadron. Recruits say in an apprehensive voice that it is stressful for them to fly over the human world. The Aurora surfaces, a hatch opens, and the Hilda corps launch their attack. Above the Misurugi, Ange meets Sala, afterwards, the two separate and Sala goes to rescue Aura. Rosalie says with a puzzled voice that the war has already begun, and then something clicks in Vivian's mind, and she locates Ange by feeling Ange's signal with her native sense and turns her Para-Mail with one wing raised higher than the other and then they set off for the place where Ange is. Afterwards, Hilda reunites with Ange, but then Ange is targeted by Chris. Chris comes, trying to capture Ange, but she is interrupted by Hilda who goes to help Ange, and then Chris scatters beams around them. Hilda has a one-on-one battle with Chris. Chris says in a voice dripping with sarcasm the fact that she was treated as a lightweight and Hilda gasps. At the river bank where the Villkiss crashed, Momoka gives mouth-to-mouth resuscitation to Ange to try to rescue her, and by so doing, Ange is revived. They stumble toward the sea to join their co-worker at the Aurora. In a back alley, while Momoka goes to look for a car, Ange encounters an enemy who is under the control of Embryo. In the middle of an aerial battle, Rosalie asks Chris with a remorseful tone why they need to make war each other. In a flashback, Chris, Rosalie and Hilda exchange gifts. Chris gets hair accessories from Hilda, but she is told then that she should make her hairstyle fit in with the hair accessory due to the fact that her hairstyle does not for Hilda's present. Chris says in a faraway tone that she put up with this kind of treatment, and their self-important attitudes, because she thought they were her friends. Thereafter, she says that Embryo proposed that he wanted to be her friend. Chris throws away her hair accessories and exclaims that Hilda and Rosalie are not her friends. Mary, who thinks that their conversation is at risk of being overheard, says in an apprehensive tone that she wants to help them even if it means disobeying orders, and then she sets off toward them. In the car that Momoka is driving, meanwhile, Embryo says that because he is the creator, he has the power to control those who use Mana. After they see the emergence of nondescript beings, who are under control of Embryo, Ange and Momoka move toward the building. Above the Akenomi-hashira, Sala does battle with Ersha and tells Naga and Kaname that it is impossible for them to recapture Aura, and that it would be a good decision for their troops to pull out and rally their army moments later Ersha seeing her children gets killed in the process. Sala tells Riza to join her. As Sylvia threatens Riza to return to the dungeon, the dragon tells her that Embryo killed Julio as she escapes and flees. Meanwhile, Ange arrives at the roof where Embryo is and meets Tusk. Tusk buys Ange some time to get away by battling Embryo. When Hilda tries to withdraw, she is attacked by Chris, but then Marika comes to her aid and covers her but dies. After Embryo teleports to the place where Ange is, Tusk also arrives there to rescue the girls, only to have Momoka attack him under control again. However it is Ange who again breaks Momoka free, who then attacks Embryo. She is shot in the chest but then runs him through with a sword and pushes him off the cliff with a car, being caught in the explosion afterwards. Tusk get Ange to his machine, and then he kisses her and says he will always be at her side. Then Tusk attacks Embryo, setting off a deadmans vest and destroying the area.
The characters in the Tekken-style fighting game Hilda and Rosalie play in Chris's flashback are Haruto and Satomi from Sunrise's Kakumeiki Valvrave anime.
