Castle of Shikigami (also known as Shikigami no Shiro in Japan) is a trilogy of arcade Bullet Hell shoot 'em ups developed by Alfa System. The overarching plot involves a mysterious castle in the country of Alcaland, which has been the subject of many "missing persons" cases. A handful of psychics have converged on the location to conduct their own investigations of the incident, each for his or her own reasons. The first game was released in 2001 in Japan, Castle of Shikigami II followed in 2003 and Castle of Shikigami III launched in 2006.

As of 2008, all three of the main games have been released in the U.S. for the PlayStation 2 (for the first two games) and Nintendo Wii (CoS III). Other ports on Sega Dreamcast (CoS II), Nintendo GameCube (CoS II), Xbox (CoS II), and Xbox 360 (CoS III) are also available, but only in Japan. The entire series also saw Japan-only PC ports. There was a Fan Translation in the works for the first game's PC port; however, in 2017, the first instalment of the series has been picked up by Degica Games for an overseas release on Steam. The second installment is planned for a December 2021 release, with a reworked translation as one of the main selling points, due to the original's infamy.

A Character Sheet is currently in the works.

Games

• Castle of Shikigami I
• Castle of Shikigami II
• Castle of Shikigami III

This series uses the following tropes:

• Berserk Button: Do NOT call Fumiko an "old maid".
• Bland-Name Product: Reika makes references to Varner Bros. and Trader Moe's in her scenario.
• Bullet Hell: Enemies in these games are capable of filling the screen with lots and lots of bullets, even moreso in the harder difficulties.
• The Cameo: Characters from the first two games appear in the third game's fanart gallery.
• Canon Foreigner: Three characters made prior appearances in other games before their eventual introduction into Castle of Shinigami.
  • Tagami (unlockable in CoS I) was originally from Elemental Gearbolt, another game developed by Alfa System.
  • Nigi Gorgeous Blue (CoS II) was originally from Gunparade March.
  • Reika (CoS III) originally comes from an old laserdisc game known as Time Gal.
• Close-Contact Danger Benefit: The Tension Bullet System. When you get close to a bullet, the player character has a red outline. Doing so makes attacks more powerful and gives additional points.
• Comforting the Widow: Kohtaro had a woman with whom he made a Childhood Marriage Promise, but who is now hospitalized. Sayo falls in love with Kohtaro. In the third game, that ex becomes the Big Bad. Or seemingly so, until you realize that all the bosses in the third game are illusions and not the real people.
• Gameplay Grading: You're graded twice through out stage in for the first two games, one for the first half of the stage and the other in the second half. In the first game, you're graded by how fast you beaten the level, the point items collected, and your overall Tension average. The second game changes the Tension average with how many x8 multipliers you where able to get. The third game changes things up where you are graded at the end of the stage instead of its two halves, adding a bonus for beating the bosses with x8 bonus as well as penalties for losing lives and using continues.
• Hitbox Dissonance: Despite how large your character sprite/model may appear, their hitbox is the tiny light that shines in the middle of their body when enemy fire or an obstacle is nearby.
• Kill Sat: Fumiko and Munchausen have Shikigami attacks that rain down lasers from above that leave behind Spheres of Destruction.
• Let's Get Dangerous!: Munchausen. When you can see his eyes, RUN.
  Munchausen: "I shall educate you. Prepare yourself."
• Life Meter: Bosses in the series have the typical gauge-type life meter, often divided for each of their phases.
• McNinja: Roger is an American that spent time in Japan and dresses like a stereotypical Ninja, but still talks like an patriotic American.
• Medium Awareness:
  • Almost everyone makes a remark at some point that shows they know they're in a video game. For example, in the third game, Fumiko openly mocks Yukari for getting excited about being back for the third game while she doesn't appear to realize that she's been demoted from Stage 4 to Stage 1.
  • Reika is another prime example, but only because she's been displaced from her game of origin. She still thinks she's in an FMV game.
• The Paralyzer: Shikou's second attack pattern, in addition to the Power Nullifier arrows above, also shoots arrows that slow you down.
• The Power of the Sun: Freedom Wind and the two bosses after her launch volleys of fireballs that look like miniature suns.
• The Protagonist: Officially, Kohtaro Kuga is the main protagonist in every installment, though Reika and Nagino are more prominent on the third game's cover art.
• Psychic Powers: The justification for most characters' combat abilities is that they're tapping into these, many with help from a Shikigami.
• Scoring Points: As a series of shoot 'em ups, you know what to expect. The series' central scoring mechanic is the Tension Bonus System (or TBS for short) players receives when their character is dangerously close to enemy fire or obstacle, going from x2 to x8. The higher the Tension, the more points the coins dropped by enemies are worth. Defeating enemies with Shikigami attacks causes much more coins to be released and they will be automatically collected to the player. At the end of each stage section (or the stage altogether in the third game), you're graded by your performance and you gain bonus points based on how well you do in the stage.
• Shout-Out: Both Fumiko and Sayo resemble Marisa and Reimu of Touhou Project, particularly their PC-98 designs. In those games, Reimu wore more traditional shrine maiden garb and Marisa in her very first appearance was a redhead with a purple outfit.
• Smart Bomb: Nearly every character has this in some form, which clears the screen of bullets and/or renders the player invulnerable while it's in effect.
  • Reika's allows her to momentarily freeze time.
  • Roger uses a Spin Attack to slice through his enemies.
• The Stoic: Emilio, a very young nobleman that seemingly takes everything in stride despite his impending demise.
• Time Police: Reika. Again, a callback to her Time Gal roots.
• Turns Red: Mini-bosses and stage bosses alike have at least three attack patterns, depending on how much HP they have remaining. From the second game onwards, their life meter is partitioned according to each segment.
• Tyke-Bomb: Nagino is an elementary school student that's actually the reincarnation of a god, inheriting powers over time as well as strong Psychic Powers for combat.
• Video Game 3D Leap: The later two games going full 3D during gameplay.
• Video-Game Lives: By default you have three per credit.
• Villain Protagonist: Fumiko. According to the manual, she's said to be as evil, if not more so, than the game's Big Bad. Her lines in games reflect this as she speaks of things like world domination.