One day middle school student Sumire Takahana meets the mysterious Lucia Nahashi, who is part of a group called Venus Vanguard. From that day on, Sumire is drawn into Lucia's ongoing battles with "The Virus", an evil spirit that snatches people's souls away. Sumire discovers that she not only has the power to see the Virus, but that she can turn into a mindless living antibody, called "Berserker mode"—an ability that Lucia finds highly useful for her purposes. It's needless to say that these events turn Sumire's life totally upside down.Venus Versus Virus started as a manga series by Atsushi Suzumi and got adapted into an anime series by Studio Hibari in 2007 (with Lucia voiced by Ayahi Takagaki and Sumire voiced by Minori Chihara). Even though it's filled with action and supernatural mystery, the focus of the series is on the relationship between Sumire and Lucia in the face of the threats they encounter.
In the manga there are more over-tones, it's even dubbed a Girls Love series, but it's still subtle.
Battle Aura: Sumire's doesn't glow, but it has enough heat to vaporize the snow in a radius around her feet.
Because Destiny Says So: A lot of things, according to Lucif. Also, maybe Lucia and Sumire's friendship, since they are the key and the gate. Sumire has Lilith's powers, which didn't awaken until she touched Lilith's brooch.
Bi the Way: Sumire has a male love interest, but it's all but outright stated she's in love with Lucia.
Keep It Foreign: A joke early in the anime revolves around saying the phrase "I love you" in English, Chinese, and Russian. In the English dub, the languages are changed to Japanese, Spanish, and Russian.
Kill 'em All: In the anime, Nahashi, Lucif, Sonoka, Ruka, Guy, and Yoshiki all die, and the fates of Lucia and Sumire aren't made clear, at least not without going into Wild Mass Guessing territory. But in the manga, the only ones who die at the end are Aion and Sonoka.
Our Ghosts Are Different: In the anime, Lola summons the ghosts of Nahashi and Lilith to restrain Lucif from attacking Sumire and Lucia. They fall under types 2 and 7 and look like blue-white versions of themselves.
Overtook the Manga: The anime goes in a different direction than the manga and also ended earlier.
Parental Abandonment: Lucia's mother is dead and her father is the big bad in the anime, or possessed by Aion, the actual main villain, in the manga. Sumire's parents are rarely mentioned, but they are alive and well.
Psycho Lesbian: Sumire, in Berserker mode! It's a little bit subtle as she is violent with the Viruses and more sexual (in a rape sort of way) with Lucia, as at one point she says they should "become one."
Also, Lucia appears to be this in the anime, when she stakes Sumire's boyfriend.
What Could Have Been: At the end of the first volume, you get to read the original oneshot, and look at the original character designs. The Viruses were more like demons, and Lucia's covered eye was different. Sumire's cousins looked very different too.
Whole Episode Flashback: Chapter twenty-two in the manga and episode seven in the anime, focusing on Nahashi's past with Lucia's parents.
Yandere: In the manga, Layla, when she's not being an emotionless girl. Although it's not romantic, she has a creepy obsession with "becoming one" with Lola.
You Gotta Have Blue Hair: Aside from the teal-haired Lucia, characters have plausible hair colors, though Sumire's red-auburn is unlikely to be seen on a Japanese person.