The Undead Invasion is an event, which happened at the Clover Kingdom's Royal Capital where an army of corpses is invading the city.
Far at the outskirt of the Clover Kingdom, Rades Spirito sits in the middle of a plain and gazes towards the Kingdom's Noble Realm. As he talks to one of his corpses, Valtos arrives through a Spatial Magic spell and informs him that their preparation is complete. Rades looks at the Clover Kingdom yet again and vows to destroy it to fulfill his revenge for his banishment from the kingdom.
The Undead Invasion
Afterwards, Rades begins to release his army of corpses on the streets of the Royal Capital. Those corpses then attack every citizen in their sight. Several city guards try to retaliate but their attacks are not enough to prevent any of the corpses from advancing even further.
As Rades's corpses are terrorizing the Royal Capital, someone quickly informs the Magic Knights who are present at the city about the situation. These Knights immediately try to organize a counterattack strategy, but Asta decides to leave as he believes that his colleagues are wasting time. He is then immediately followed by Leopold Vermillion.
Subsequently, Fuegoleon Vermillion quickly divides the other Knights into several groups to confront the invasion before leaving to catch up with his brother alongside Noelle Silva. Asta finally reaches Rades, who is in the middle of intimidating a little girl. As he recognizes Asta's affiliation to the Black Bull squad, Rades tries to attack him by using the corpses that had been defeated. Unfortunately, none of the corpses respond to his order, which gives the little girl a chance to escape from Rades and to hide behind Asta. The former Magic Knight then summons a new batch of corpses to attack the young Knight as the fight begins.
In the other districts, the other teams of Knights have reached their designated locations and are confronted by hundreds of corpses. As they learn of their enemies' particular characteristics, all of them are in agreement to mercilessly decimate every corpse on sight. However, Noelle Silva does not seem too eager to fight against the corpses after her brief encounter with her older siblings. This results in her hesitating to assist Asta and allowing several corpses to ambush her. Fortunately, Fuegoleon is swiftly able to save her. He reprimands her but also conveys several words of encouragement.
After a while, the Magic Knights are finished eliminating all of the corpses with minimum effort. Nozel Silva begins to grow suspicious with their enemies' lack of power as he is pondering about the enemies' true objective. At that moment, a Spatial Magic spell activates under the Knights' feet. Before they could even react, the spell manages to teleport almost all of the Knights who were defending the city to location a considerable distance away from the Royal Capital.
After most of the Knights are out of the picture, Catherine finally reveals herself to the Royal Capital's citizens while also giving her remarks over the unsuspecting Magic Knights as they easily fell for their trap. She then begins to assault them by absorbing their mana. Fortunately, Yuno who managed to escape from the Spatial Magic spell, immediately confronts her and the fight between them begins.
On the other side, Asta is struggling to defeat Rades's corpse, No.2 - Alfred, while Leopold and Noelle is occupied with another corpse, No.3 - David. Seeing the young Knights' struggles, Fuegoleon decides to enter the fight and incinerates Alfred.