Saint October

Kotono Hayama is a young girl who lives with Joshua in a church. She and her best friend/admirer, the wealthy Natsuki Shirafuji, help out at the Kuroki Detective Agency. Their story begins with children being kidnapped, with a certain boy, Ewan, being the culprit. Kotono befriends him, and he bestows upon her the power to transform into a Magical Girl.

As it turns out, the Reverse Corporation, a nefarious group of tarot card users, has been scouting out Arcana City to find Ewan for their boss, President Kurtz. Kotono, Natsuki, and a strange newcomer named Misaki Hijiri form the Goth Loli Detective Agency to solve the city's problems as Black Loli, White Loli and Red Loli.

Saint October was an Anime First series by Konami, airing in the winter of 2006 for 26 episodes.

Tropes used in Saint October include:

Almighty Janitor: Eddie Tsukahara, Reverse's janitor, is able to repair Kotono's broken Justice card with no ill effects.
Anime Chinese Girl: Seiran, an early villainness with wind powers.
Avenging the Villain: Esmeralda is Herlock's kid sister, set to get revenge on Kotono for killing him.
Brainwashed and Crazy: Almost all of Arcana City in the finale. Including Joshua.
Bunny Ears Lawyer: President Kurtz is a bit of a weirdo. He experiments with random things in his office, seemingly unfazed by anything. But when he gets mad, he gets Laughing Mad.
Butt Monkey: Koshiro Kuroki, the (former) owner of the detective agency. He is useful a few times, but is generally on the recieving end of bad luck and punishment.
By the Power of Grayskull: The three Goth Loli Detectives have long, elaborate phrases when they transform.
Catch Phrase: Whenever Misaki is called "Misaki-chan", she responds with "Don't call me '-chan'."
Cannibalism Superpower: Kurtz eats Ewan in slate form to gain his power and become king of the world.
Deliberately Cute Child: Esemeralda
Elegant Gothic Lolita: They are the Goth Loli Detectives.
Everybody Lives
Everything's Worse with Bears: Played straight with a bear that attacks Kotono and Ryouhei on their camping trip, but it turns into an Androcles' Lion for Misaki. She befriends the bear and names him Hiroshi Piroshiki Romanov. He even becomes her mount!
Face Heel Revolving Door: Ryouhei starts off as not affiliated with Reverse at all, joins them, is convinced to turn away, and then rejoins when the mass brainwashing begins.
Fortune Teller: Artista
Green Lantern Ring: Misaki's arrows are incredibly versatile, transforming into whatever she calls out.
Imaginary Love Triangle: Cecil, a fellow student of Kotono's, thinks she's in love with Ryouhei, and even gets tarot powers to take her down. When it turns out they're not close at all, Cecil lets Kotono purify her.
Love Makes You Crazy: Sophia is in love with Kurtz, and suffers for it.
Luke, I Am Your Father: Ash is Kotono's father. Joshua took her in because he was a neglectful parent who tried to hurt his own daughter once he got his hands on tarot powers.
Magical Girl
Mega Twintails: Esmeralda. She can do a lot with them. Including storing things.
Morphic Resonance: When Suzukichi and Osuzu transform from sparrows into humans, they're still very visibly sparrowish.
My Name Is Not Durwood: When Suzukichi and Osuzu deliver a tape with a warning message to Kotono and company from Esmeralda, none of them can remember her name. She's accounted for this.
Non-Human Sidekick: Kafka, a familiar of some sort.
Ojou: Natsuki.
Premiseville: It's called Arcana City, and there are tarot cards involved.
Super Empowering: Ewan and Kurtz, being slates, can give the power of the tarot cards to anyone else.
Taking the Bullet: H.P. Romanov takes a few arrows for Misaki in episode 25. Her brother did the same thing in her backstory.
Tarot Motifs: All magical powers in the show are drawn from tarot cards. Reverse holds most of them.
Team Pet: Two. Nike the parakeet and Xupery the cat.
Theme Naming: There are two patterns to the girls' names. Kotono, Natsuki and Misaki spell out "Konami". There's also "Hijiri" (聖), the "To" in Kotono (小十乃) and the "Tsuki" in Natsuki (菜月), which together spell out 聖十月, the Japanese translation of "Saint October".
Trademark Favorite Food: Cake, for all the Goth Loli Detectives. Joshua makes them a new one every episode.
Transformation Sequence: A little more visceral than the usual magical girl fare. Fruit pulp covers their bodies and transforms them into their outfits.
Undying Loyalty: Ash lives for Kurtz.
Weapon of Choice:
- Heroes Prefer Swords: Kotono
- Fighting with Chucks: Natsuki
- The Archer: Misaki.
Verbal Tic: Esmeralda exchanges all "shi"s for "chi", such as calling herself "atachi", and ends every sentence with "de chi".