On Christmas Eve the Abyssal Shaft Raid Party come upon Ruseato of Seven Prison (Luseat of the Seventh Garden in the Crunchroll subs), a level 97 raid boss. After doing some recon, they engage the boss in battle. Shiroe predicts they have a fifty percent chance of success.
The first time the boss does an Area of Effect (AoE) attack there are two instant kills (Enkaatanto & Federico) and three badly wounded (HighlandSky, Junzou & Ragoumaru). They revived the dead and healed the wounded while Sasameyuki kept count for the ability cool down time. Junzou and Ukiyo note that while that skill wasn't new, it was a lot more powerful than in The Nine Prisons of Heroes. He also has new moves which are equally as powerful.
The second time he does the attack everyone survives and they gain some confidence. Ruseato then does a new AoE attack called Evil Poison Root which prevents all those affected from moving and cause some damage as well as drops attack speed and damage. Ruseato also ignored Dinkuron's Anchor Howl and then started spinning around his giant ax which then flew around the room hitting most (if not all) those present. The result was eleven dead.
When Dinkuron stepped back to be healed and Naotsugu took over as tank, the raid boss started changing, shedding his dark exterior to become his True White Knight Mode. Ukiyo was surprised and said that before you had to trigger something in the dungeon for that to happen but now he seemed to be able to do it whenever he wanted. The fallen slivers of his armor quickly rose up to become Shadow Vanguards. They kill the Shadow Vanguard and realize that once killed they return to Ruseato and heal him resulting in him returning to his Black Knight form with more HP.
After this happens several times Shiroe says the problem is the number of attackers. There number of Shadow Vanguard is directly related to the number of people who attack the boss; if you drop the number of attackers, there would be less of the Vanguard to deal with. They change the plan to only have only those with the strongest attacks hitting the boss, thus limiting the number of Shadow Vanguards that appear.
Wiped OutAs the raid party slowly whittles down Ruseato's HP, they fail to notice the gates behind them slowly opening. Meanwhile, Demiqas furiously attacks Ruseato and the Shadow Vanguard, aiming to raise his levels, polish his skills, and win better equipment in order to defeat Shiroe. As Sasameyuki counts, a large shadow suddenly appears over him. Looking up, he barely manages a cry when Tarutauruga of Fourth Prison smashes him with its club, instantly killing him. As William mutters its name in shock, Ukiyo's scream drags their attention to Ibura Habura of Third Prison, which had appeared in front of the first party. The combined assault from 3 raid bosses wipes out the the entire party, as they curse the impossibility and unfairness of the raid.
After the raid party wipes out, Roe2 is seen rising out of the snow in a separate location.
Upon his death Shiroe is relieves memories of his lonely childhood back in the real world. He comes to understand what William meant when he said that memory loss was trivial; in Shiroe's case, he forgot the name of an Indian restaurant that used to be on his street before it closed down.
After finding the resolution to move on, he is then transported to Mare Tranquillitatis which is a reproduction of the Moon. There he meets Akatsuki. After spending some time with Akatsuki they both vow to try again, after which he awakens back in the Abyssal Shaft.
- When Shiroe looks at Dinkuron's status screen in one shot, the status screen is not properly mirrored, and faces us rather than him. This mistake is repeated multiple times in the episode.