WARNING: The following contains spoilers for The Irregular at Magic High School Season 2, Episode 5, "Visitor Arc V," streaming now on Funimation.
The separate factions investigating the murderous Vampires finally decided to work together after Tatsuya shared some valuable information about the parasites controlling them. Turns out that decision came just in time. When Lina's friend and fellow USNA agent Mia suddenly appears at First High School -- as part of a magical equipment delivery team -- Tatsuya and Mikihiko both sense something is off about her. An otherworldly parasite is revealed at last, and an electrifying battle becomes especially dangerous for Erika as an inner conflict leads her to become the parasite's new target.
Before the explosive action, however, Tatsuya and Miyuki get a call from their friend and classmate Shizuku, still studying abroad in the United States. She shares newly acquired information about the parasites' likely origin -- American scientists' secret black hole experiments. Tatsuya's lengthy theory on alternate dimensions and gravity goes over Shizuku and Miyuki's heads. He believes the experiments affected the dimensions' gravitational pull and caused the walls separating them to waver, thus allowing the parasites to cross over into the human dimension. The major question: how can they fight the parasites when they can't even see them?
Lina's having a rough time after her disheartening defeat to Miyuki. Her friend Mia, who she had been excited to see, arrives at First High School as part of a team delivering some new magical equipment. At first, Lina's excited to see her, but she and all the other students recognize an unnatural being has entered the school's campus. Mayumi, monitoring from afar, asks Tatsuya to check it out while all the other factions appear on the scene as well. Tatsuya and Mikihiko both use their specialized eyesight to see that Mia, though appearing human, is now a Vampire with a parasite somewhere inside her.
As ever, Erika is first to leap into the action by attacking Lina -- who she wrongly perceives as an enemy working with the Vampire -- before going after Mia. Though her goal is pure, Erika's temperamental nature puts her in extreme danger with this particular foe. As previously revealed, the parasites require a host to survive in this realm and therefore choose humans who are in a dark place and can't control their own emotions.
When Mia the Vampire is eventually frozen in place by Miyuki's powerful ice magic, the parasite self-destructs, killing Mia and attacking the entire group from the sky. With Mia dead, the parasite needs a new host, and Erika -- who has been upset over Leo's hospitalization and a perceived over-reliance on Tatsuya -- is its prime target.
Similar to how the previous episode brought Miyuki back into the spotlight, this battle allows the shy and soft-spoken Mizuki to play a crucial role: her hypersensitive eyes can "see" otherworldly spirits and beings. The rest of the group -- Tatsuya, Miyuki, Lina and Katsuto -- tries to defend Erika and each other but can't actually see where the parasite is, so they're fighting mostly blind.
As the parasite continues attacking with enormous amounts of electricity, Mizuki and Mikihiko combine their spiritual magic abilities so Mizuki can tell the others where to aim their spells. Though the parasite ultimately escapes, the group doesn't suffer any lasting damage thanks largely to Mizuki and Mikihiko.
Much of the cast finally came together to battle the parasite, but distrust and secrecy remain among them. Mayumi suspects Tatsuya is somehow planning to use all these events to his own mysterious end. Erika and Katsuto have no love or trust toward Lina, while Erika had also forbidden Tatsuya from taking Mia the Vampire before the parasite self-destructed. Lina, who still has to play the American transfer student role, has no authority over the situation and cannot reveal her Angie Sirius identity any further after Tatsuya and Miyuki learned her secret. She's also lost a dear friend, giving her an even more personal reason to investigate and destroy all the parasites. With the way Lina's current arc is trending -- multiple defeats coupled with Mia's death -- could she be a future target for the parasites?
For now, the escaped parasite has found a new host, seemingly a female humanoid. As a humanoid presumably feels no emotions, could the parasite attempt to communicate with Tatsuya and the others rather than attack? Do they feel desires of their own? What is their true purpose in crossing dimensions? For all the questions answered so far, many more still remain. With Tatsuya and co. working toward their own ends with plenty to gain -- or lose -- on behalf of their influential families, conflicts will likely continue to arrive from multiple angles.
