Shikigami no Shiro (式神の城), released as Mobile Light Force 2 in the US and Europe, is the first game in the Shikigami no Shiro series.
For the storyline: In July 2005, a string of serial murders took place in Tokyo, where all the victims were female and killed by external injury. The killings took place within 20 hours. On July 21, the 31st victim was found. The police force classified the case as special crime #568, and began to seek investigators from occult sources. The story begins on July 23, with the 32nd victim.
For gameplay: Controls are Normal attack (Tap attack button), Shikigami attack (Hold attack button for over 0.3 second. In this mode, player moves at slower speed. When switching to shikigami mode, all on-screen items are automatically retrieved.), and Special attack (Press Special attack button. Player is invulnerable when the attack is in effect). When destroying enemy in shikigami mode, the multiplier also applies to the number of items dropped by enemy. When an enemy is destroyed in shikigami mode, all item dropped by the enemy is automatically retrieved. When destroying enemy in shikigami mode, the multiplier also applies to the number of items dropped by enemy. When an enemy is destroyed in shikigami mode, all item dropped by the enemy is automatically retrieved.
There is also a Tension Bonus System (TBS): When the player is close to an enemy bullet, the player gains multiplier based on distance of bullet from player's centre, with closer distance receiving higher multiplier. The multiplier ranges from 2x to 8x. Score multiplier is applied when destroying enemy or retrieving item.
Source: Wikipedia, "Mobile Light Force 2", available under the CC-BY-SA License.