Summon Strike (サモンストライク) is a fighting game developed and published by Namco for the PlayStation 2, as one of the console's launch titles. It tells the stories of Kite's Summon warriors before they formed their ties to the Azure energy. This game is the prequel to the Robot Summoner Kite series, as well as the first game to introduce the fighting aspect of the series, which will then be carried over to the main series (although some games tend to abandon that feature).
Summon Strike's gameplay is inspired by the likes of Squaresoft's Tobal No. 1 and Capcom's Rival Schools, but it has a fighting system reminiscent of a hack-and-slash type of game. It still has the basic gameplay of a 2.5D fighting, where the simple goal is to fight the opposing character and to win by reducing their health to zero. Characters also have their various special abilities unlike from the main Robot Summoner Kite series. To use these attacks, however, the player must have the required azure as indicated by the "azure bars" located under the players health. Using the technique drains the azure bar (which can be regained through various methods, including special, character specific methods for some characters). These special techniques are not performed in real-time, however; once successfully executed, a cinematic takes place, where the player either has to fill a bar to a specific level or hit buttons illustrated in the corner of the screen faster than their opponent to assure the attack is at its full strength.
Two years before the events of Robot Summoner Kite, a man named Lemmet has traveled across the galaxy, searching for the variants of Azure. In the past he was known for starting tournaments called "Azure Grand Prix" in which he chooses the descendants of the most strongest warriors and forces them to fight various opponents in order to prove which of them is worthy of becoming an Azure warrior (or, in a later case, a Summon). He does a similar event after discovering the blue Azure, and now warriors from across the galaxy must fight to become the Azure heroes of the future.
In Summon Strike, there are 12 default characters, four of each from 3 different groups (Elemental, Physical, and Weaponized). There are also 3 unlockable characters in each group, nine in total. In addition, there are 21 characters to choose. They are all different warriors who later become the Summons Kite uses.
- Marla: The Flame Sorceress. She is said to carry the legacy of the flame sorceresses before her and decides to enter Lemmet's tournament.
- Criss: The Ice Mage. Secretly trained by her older brother on the arts of ice magic, she chooses to enter the tournament to test out her abilities.
- Wyatt: The Electromancer. An accident has led him to having the electric abilities he has now, and he joins the tournament to prove he is worthy of becoming an Azure warrior.
- Relik: The Golem. He wants to prove that the Golems of Planet Terruna can have a sense of heroism and he does this by entering Lemmet's tournament.
- Sol (UNLOCKABLE): The Light Jester. His wish is to bring light to the far ends of the galaxy with his trickster abilities, which is why he enters the tournament.
- Typhoon (UNLOCKABLE): The Storm Monster. He enters the tournament mainly to help create weather that will benefit other planets.
- Thornn (UNLOCKABLE): The Plant Alien. She wants to learn about the beauties of the galaxy, so she joins Lemmet's tournament to prove herself as an Azure warrior.
- Hiroji: The Fighter. He claims to be not only the strongest fighter in the universe, but also the strongest Azure warrior, for which he joins the tournament.
- Blue Star: The Wrestler. As he participates in Lemmet's tournament, he believes he can make a change in his life by using his abilities to help people.
- Pinpoint: The Porcupine. He unintentionally got invited into the tournament while looking for a hideout from Lemmet.
- Formula Zero: The Race Car. It has been rebuilt by scientists into a robotic combatant in order to enter the tournament and become an Azure Warrior.
- Jumper Man (UNLOCKABLE): The Super-Jumper. A superhero with extraordinary jumping abilities, he chooses to enter the tournament.
- Sufia (UNLOCKABLE): The Ball Morpher. It was sent into Lemmet's tournament after crash-landing from its planet Polys, and it wishes to become an Azure Warrior.
- Prayer (UNLOCKABLE): The Mantis. Its goal was to enter the tournament not to become an Azure Warrior, but to steal the Azure for its master.
- Golrang: The Cutter Robot. He is revealed to be a Quargon robot whose main asset is his boomerang weapon, which he uses to his advantage in the tournament.
- Xander: The Swordsman. A traveler on the search for the killer of his mother and brother, he enters the tournament to become an Azure warrior.
- Dyna Bang: The Bomber. An elf-like creature from the planet Criosia, where he is a criminal known for stealing explosives. He uses these explosives in the tournament.
- Rebecca: Also known as Milady. She hails from a royal kingdom in Neo-Earth and she joins to become an Azure warrior, as unusual as her wish sounds.
- Raizo (UNLOCKABLE): The Ninja. Accused for the slaughter of many victims, he seeks to better himself by becoming an Azure warrior in the tournament.
- Brutus (UNLOCKABLE): The Hammerer. He likes to boast about his strength and hammering skills, so far as to enter the tournament to become an Azure warrior.
- Vulcan (UNLOCKABLE): The Jet Mech. A mere anthropomorphic jet upgraded with weapons, he strives to become an Azure warrior by entering the tournament.
- Lemmet: A space outlaw who is the deuteragonist of the game. He has heard of the Azure energy wandering across the galaxy, and claims it to begin the Azure Grand Prix. He was known for starting the Azure Grand Prix after claiming other Azure energies, most of which turned to be victorious. These tournaments are revealed to be experiments for transforming a warrior into a Summon tied to the energy. While this tournament occurs, he managed to transform Agil into the Destroyer.
- Agil: The Destroyer and the final boss of the game. During the events of the tournament, he struck a deal with Lemmet to be tested by the Azure energy and, as a result, he became the Destroyer. With infinite destructive power, he poses a threat to the future Summons (including himself). After a character defeats him, he destroys Lemmet's laboratory, including the capsule containing the Azure energy, and out of it comes an Enerbeast, the Azure Dragon. After the events of the game, Agil is in hiding, but disguised as a human...
- Cape: A scientist working for the then-existing Olympus. He is known as the Red Jet because of his quick heroics and knowledge in science. When he witnesses the arrival of Lemmet and the announcement of the Azure Grand Prix, he and the other Olympus members plan on an ambush to take the Azure energy from him. Later games reveal that he is the father of the series' protagonist Kite.
- Kite: The robot summoner here is a human boy who is the son of Cape. He remembers seeing the Azure Dragon one night and wishes to see him in the future. A cruel fate awaits him later on, though...