Ga-Rei

Ga-Rei is a 2005 manga series by Hajime Segawa about Ordinary High School Student Kensuke Nimura and definitely not ordinary high school girl named Kagura Tsuchimiya. After an incident involving a giant monster ghost baby Kensuke follows Kagura into her world of supernatural peril.

Ga-Rei Zero is a Prequel anime series that acts as Yomi (the first Big Bad)'s Start of Darkness. It is also much Darker and Edgier, Ga-Rei is quite light in comparison.

Tropes used in Ga-Rei include:

Accidental Sacred First Kiss/Crash Into Hello: How Kagura and Kensuke meet. It's quite painful for the latter, as the former runs into him on a motor scooter.
Action Girl: Many, Kagura, Kyouko and later Isoyama Izumi are the primary examples.
Afterlife Express: Ghost train, rather.
All Myths Are True
Aloof Big Brother: Souzaemon, Kyouko's older brother, is both cold and extremely competent. Naturally, he rubs Kensuke the wrong way.
Apocalypse Maiden: Yomi. She just can't catch a break.
Art Evolution: In leaps and bounds. Just compare the cover of Volume 1 to Volume 7.
As Long as There Is Evil: The source of the Sesshouseki's power.
Back from the Dead: Yomi. More than once.
Beach Episode: They go to a water park, too.
Big Damn Heroes: A big one in Chapter 44 with Kensuke, Tsuina, Noriyuki, and Shizuru, i.e., everyone you've been expecting to show up for the past few chapters.
Black Eyes of Evil: Anyone taken over by a Sesshouseki, complete with white Hellish Pupils.
Bland-Name Product: "Poeky". Similarly, the fake clothing brand Productive Emotion.
Blank White Eyes: Used extensively when the characters are super-deformed.
Blinding Bangs: Izumi/Yomi, though not consistently.
Body Horror: Tons and tons. They fight evil spirits, after all.
Brainwashed and Crazy: Kagura, under the influence of the Kyuubi.
Butt Monkey: Yomi.
Cain and Abel: Yomi and Kagura, in that order.
Cat Fight: During Kagura's and Shizuru's festival fight, Noriyuki starts taking bets for who's going to win. Fanservice is mostly absent, though, since they're pretty beat up by the end.
Chained by Fashion: Byakuei is chained to Kagura as an indication that it's sealed into her.
Chivalrous Pervert: Noriyuki. Especially when it concerns Shizuru, interestingly enough.
The Chosen One: Kagura.
Clingy Jealous Girl: Izumi definitely fits this
- Yomi actually shows a few glimpses of these when it comes to Kagura or Noriyuki. While it may not be clingy, it's definitely a scary jealousy
Cool Big Sis: Yomi.
Cool Sword: Kagura's appears to be a laser; one of Yomi's is made out of several smaller blades attached to a single one in the center. Check the Power of Love page to see what Kensuke's Michael Revolution is capable of.
The Corruption: Yomi struggles with it whenever she has screen time.
Dark Action Girl: Yomi, Shizuru.
Dead Big Sister: Kagura killed Yomi while Yomi was being controlled by the Sesshouseki (see Ga-Rei Zero). It doesn't seem to bother her at first, but it eventually takes its toll.
Decoy Protagonist: Kensuke
Demonic Possession: Izumi turns into a giant demon spider before Yomi takes over her body.
Demoted to Extra: Kensuke of all people gets this treatment once Kagura forgets about him.
Disney Death: Kensuke is killed, but Kagura resurrects him with the power of the Kyuubi. She resurrects Yomi, too, though subconsciously.
Damsel in Distress: Inverted with Kensuke. While he's lamenting about having to be rescued, a picture of an actual distressed damsel even shows up in the panel.
Does This Remind You of Anything?: Replace "black/white priestess" with "lunar/solar priestess", and you start getting Kannazuki no Miko vibes.
Earn Your Happy Ending: It look a lot of heroic sacrifices, but they did earned it!
Easy Amnesia: Happens to Kagura. Her memory is restored over time, though in the meanwhile it leads to Amnesia Danger.
The End of the World as We Know It: Planned from the start. There's a reincarnation planned, but everyone on the planet has to die first.
Eye Scream: Kensuke's eye gets slashed open when he tries to protect Izumi from Kirin. Since he no longer has a Sesshouseki inside him, he never fully recovers, and it leaves a huge scar.
The Faceless: Lord Tamamo.
Face Heel Revolving Door: Yomi starts out heroic in the beginning of Zero, turns heel after being implanted with a Sesshouseki, turns face after being brought back to life, and in current chapters, is forcibly turned back into a heel. Girl can't catch a break.
Furo Scene: Several. They're equally as generous with fanservice as they are with character development.
Fire-Forged Friends
Gotta Catch Them All: The Sesshouseki, in order to summon the Kyuubi.
Groin Attack: Kagura to Kensuke. It's so painful Kensuke even art shifts, and is left lying there for quite a while.
Hard Gay: Koji Iwahata. The big badass ex-mercenary.
Healing Factor: One of the benefits of having a Sesshouseki embedded within you.
Heir to the Dojo: Played straight with Kensuke. His parents are kendo masters, which is the reason he can handle Michael XII.
Heroic Sacrifice: Who else but Yomi. At least she gets her break.
Humongous Mecha: The spirit armor used by Tsuina. They're basically mechs that run on spirit energy.
Ice Queen: After her resurrection, Yomi is like this to pretty much everyone save Kagura.
Inaction Sequence: Chapter 45, which is more or less an Info Dump about The End of the World as We Know It.
Incest Subtext: While not blood-related, there is A LOT of subtext between Yomi and Kagura, two people who see each other as sisters. May also count as Not Blood Siblings.
Interrupted Suicide: Yomi, whose suicide is interrupted by Okama.
- In the same chapter, Izumi's dad, now undead, shapeshifts into his own monster of sorts.
Karmic Death: Kazuhiro Mitogawa is killed by his own mother, whom he had been aiming to resurrect.
Kissing Discretion Shot: Everytime Kensuke and Kagura are about to kiss the manga takes some other angles or just skips some seconds.
Knife Nut: Shizuru needs hers to summon Kurofoudo.
Last-Second Word Swap: Kagura is about to confess her feelings for Kensuke...and then tells him it was Iwahata who said he liked him. Nice going there...
The Lifestream: The Reimyaku.
Love Triangle: Quite a few for a relatively short series, all of which with Kagura in them (although not necessarily in the middle every time). There's Kensuke/Kagura/Shizuru, Kensuke/Kagura/Izumi, Kensuke/Kagura/Yomi, and Kagura/Yomi/Noriyuki.
Made of Plasticine: The evil spirits, who regularly get shredded into pieces by Kagura and company. Justified since they're no longer human.
Magnetic Plot Device: Yomi gives off miasma, which attracts evil spirits.
Maybe Ever After: Arguably Kensuke and Kagura, after tons of Ship Tease and the culmination of Kagura actively using The Power of Love near the finale, with their relationship...doing something.
Meaningful Background Event: In the last page of the final chapter, the whole group is reflected by a puddle on the ground. Look at it close enough, and you can see Noriyuki in the reflection, even though he isn't physically with the group. This signifies his status as a ghost before the epilogue.
Meaningful Name: The kanji in Yomi's name mean "underworld". It should be no surprise she was picked by Naraku.
Mental World: Izumi goes into one and refuses to come out while Yomi has control over her body.
The Mentor: Yomi to Kagura; Noriyuki to Tsuina...and possibly to Shizuru.
Mind Probe: Setsuna has the Eye of Satori, which allows her to read minds.
Mr. Exposition: Kensuke fills this role from time to time, usually at the beginning of each chapter.
Only Sane Man: Kensuke
Onmyodo: Used extensively by the Countermeasures Department, but mostly by Kyouko and Souzaemon.
Parental Abandonment: Kagura, Yomi, Shizuru, Kensuke to some extent... Parents are pretty much never talked about.
The Power of Love: Used to cross dimensions, believe it or not.
The Powers That Be: They're possibly the ones attempting to end the world.
Put on a Bus: Kyouko, Shizuru, and Noriyuki all leave at the end of the Kyuubi arc. Fujiko retires, and the entire Countermeasures Department dissolves. It's not long before the action gets going again.
Ret Canon: A few of the manga's later flashbacks borrow either characters or scenes from the anime. At this point, the anime could be considered manga canon.
Rich Bitch: Shizuru. She gets better, though.
Romantic False Lead: Shizuru to Kensuke. Later, Yomi to Kagura, at least until Kagura regains her memories.
Running Gag: Kensuke gets hit by vehicles really often. It's a wonder he hasn't died.
Schoolgirl Lesbian: Izumi.
Sealed Evil in a Can: The demon king from the first arc is sealed beneath the city.
Sealed Inside a Person-Shaped Can: Byakuei within the Tsuchimiya heirs.
Slasher Smile: While controlled by the Sesshouseki, Yomi sports these now and again.
Shipper on Deck: The nameless tanuki.
Shown Their Work: Chapter 48 features scenes taking place in Washington, The Vatican, and London. All of the scenes actually look like the cities they're representing.
Sliding Scale of Idealism vs. Cynicism: Waaay over to the idealistic side. It's quite pointed when compared to its Darker and Edgier anime.
Sleep Mode Size: Byakuei, after the end of the Kyuubi arc.
Spirit World: Lord Tamamo's Garden.
Split Personality: Izumi and Yomi. Lampshaded by Yomi herself when Kagura isn't sure who she's talking to.
Team Pet: Despite not having a name, the baketanuki frequently saves the lives of the heroes by turning into a giant wall. It's even used as a sled at one point.
Trauma Conga Line: The entire Ga-Rei (including the prequel anime) is just one long series of one tragedy after another befalling Kagura. When you read it in one sit, Kagura begin to look like Shinji Ikari, minus the whininess.
The Power of Love: Apparently this is how Kagura gets the powers of the White Priestess. Not revealed to cornily...until suddenly Michael goes, "Kagura! It's time to use the power of love!"
Took a Level in Badass: Shizuru, after her training with Noriyuki.
- Kensuke takes a few over the course of the manga as well.
Villainous Crossdresser: Okama Zankurou.
- Okama is slang for "drag queen" in Japan.
The Virus: Naraku seems to be some form of this.
Wham! Episode: Chapter 33, when it's revealed that Kagura lost her memories, and to a certain extent that Yomi's come back from the dead.
What Do You Mean It's Not Awesome?: Master Michael's Hepburn, a snowball machine gun.
What Happened to the Mouse?: At the end, what happened to Noriyuki? Sure, Yomi merged with Kagura, but does that mean she took Noriyuki with her?
- In the epilogue he's chilling as a ghost
Worthy Opponent: Shizuru, to Kagura.
Yakuza Princess: Shizuru.
You Have Outlived Your Usefulness: Mitogawa rips Yomi's Sesshouseki out of her head once she is defeated by Kensuke and Kagura, and she fades away, presumably to arrive at The Lifestream a cleansed soul. Really, though, he just wanted the Sesshouseki for himself.