Gekisho

Gekisho (激掌) is a popular series of featured in the Toaru Majutsu no Index universe. Created by the game company, Weed, the series is popular enough to spawn 8 sequels, the latest known sequel is Gekisho 9, and is a favorite of Tessou Tsuzuri.

Gameplay
It employs basic fighting game mechanics. Players are able to choose from a variety of characters to fight the computer or a human-controlled opponent. Each character has a lifebar on the top of the screen, the goal is to diminish the opponent's lifebar before the time runs out, the winner is the one who is able to empty their opponent's lifebar first, or if the character's lifebar has higher points than the opponent.

Each character also have bars below them that indicates the amount of power they have, each time a character hits an opposing character, the power bar fills up, allowing the character to perform much more powerful moves the higher their power bar is filled up; after executing a move, the power bar is then diminished depending on how much power the move required.

The game has six buttons and the directional joy stick for the player to perform moves on their character.

Available Characters
These are characters that are already available when one starts a game.
 * Tatumi Gin - Can use fireballs.
 * Kathy - Control of electricity on her right hand.
 * X-Zairu
 * Kappa - Based on the of Japanese mythology.
 * PG
 * Cloud
 * Lui-G
 * Monmon

Unlockable Characters
List of known characters that can be accessed after performing specific conditions in the game. There is also another unlockable character in the game that seem to sport a and a  though it's name is blurred to the point of illegibility.
 * Jamie Whitman - Tessou Tsuzuri's favorite character.
 * Shi Shio
 * Kirman Call
 * King Duck
 * A-Ma Doomi
 * Q2
 * Kashi
 * Ura Shim
 * Accel Erator - Easter egg by.

Poltergeist Arc
The game is first featured in episode 17 of the anime, where it is discovered that Tessou Tsuzuri is fond of the game, with her favorite character being Jamie Whitman. Here it is revealed that Gekisho 9 is now a fairly old game, and that Weed, the producers of the game has yet to produce another game for quite some time.

Tsuzuri is seen playing the game in Playland Gau, after becoming depressed by her recent shift as a member of Anti-Skill. Here, she is challenged by Kounoue Haruki to a game, using Tsuzuri's favorite character as well and is defeated by him. Though she is happy after the game, and later escorts Haruki to the vicinity of his residence, here she wishes that they make a new game of Genhiko. The next day, she discovers that Haruki has moved to another school, Zassou Academy, where Weed prepares it's students to become video game developers, much to Tsuzuri's delight.