The FX-R4 Peace and the FX-K2 Love are the main protagonists of the 1991 arcade shoot 'em up Lethal Thunder / Thunder Blaster. They are pair of starfighters sent by humanity to defend Earth from an invading force from an alternate dimension. Both fighters possess rather unique weapons that prove to be useful in combat.
History[]
For many years in our universe, a global war plagued the planet Earth, causing the conflict to spread well above the atmosphere. Due to the use of illegal reactive weapons and extra-dimensional ordinances, war worsens to the point that eventually the planet's own ecosystem is subjugated, causing the fabric of the space surrounding the planet to transform.

At the same time, an extraterrestrial force from an alternate dimension gains intelligence regarding the events that unfolded in the aforementioned universe via their military supercomputer, and exploited its conflict as a means to launch an invasion while it was vulnerable. Eventually, in the year 2122 A.D. they launched their invasion in motion, and broke through the dimensional barrier into our universe. The enemy was well prepared, as they had full knowledge of the planet's technology. With the planet still reeling from the recent conflict, they appeared to be defenseless to the point that fighting back these alternate opponents was futile. It appeared as though the enemy invasion was going to be successful... that is until two starfighters named the FX-R4 Peace and the FX-K2 Love were launched to fend off these extra-dimensional invaders. Armed with a chargeable primary weapon and a reusable bomb-like device known as the Thunder Ball Unit, the two fighters became humanity's best chance to stop the invaders.
The two starfighters penetrate through the enemy's forces through outer space and various environments, where they proceed to eliminate their army's units and commanders using their unique weaponry. Eventually, they confront the enemy's leader codenamed Gold Mine, where despite its defensive capabilities, the two fighters manage to destroy. Following Gold Mine's destruction, the two starfighters will be met with one of four endings depending on their performance:
- Ending no. 4: If all bosses except Gold Mine escape, the delay in the destruction of the Alien base results in their forces successfully invading Earth, resulting in the planet's destruction and rendering it uninhabitable.
- Ending no. 3: If most of the bosses escape, the Alien Base will be destroyed, however doing so will lead to the invasion force surrounding Earth, leaving the planet's fate in a cliffhanger.
- Ending no. 2: If at least one boss escapes, the two fighters pilots are notified that despite destroying the alien base, the battle is not over yet, stating that the battle against the Alien Starship is only beginning.
- Ending no. 1: If all bosses are destroyed, the alien base, as well as all of their forces are completely wiped out. Peace is restored to Earth, and the two fighter's heroism will not to be forgotten.
Weapons[]

The FX-R4 Peace and the FX-K2 Love possess two rather unique weapons: the first is one of four primary weapons which gradually increases in power when the weapon is fired in rapid succession (indicated by a power meter on the left side), the second weapon is a reusable bomb-like device. The primary weapon can be switched by obtaining colored modules in the form of power-ups.
- Vulcan - the default primary weapon of the two fighters, it fires a standard shot forward, destroying small enemies instantly while requiring additional firepower on larger ones. When powered up, the number of shots and their size increases.
- Fire - fires a large flamethrower straightforwards. The weapon has the highest damage output, but has the narrowest spread of all primary weapons. When powered up, the size and range of the flamethrower increases, while at higher levels, an additional helix laser is fired in the same direction for added power.
- Laser - fires laser forward, which proceeds to make a 90 degree turn towards the enemies it tracks, it is highly versatile in most combat situations. When powered up, the width of the lasers increases.
- Ball - fires a spread shot of fireballs which can be contracted or dispersed depending on the fighters' vertical movement. Concentrated shots have a narrow spread, but deal more damage, while dispersed shots will cover a wide area, but deal less damage. When powered up, the size of the shots will increase.
- Thunder Ball Unit - a reusable bomb-like device which when deployed, creates a explosion of variable size, destroy all small enemies and projectiles whilst also causing heavy damage to larger enemies in its radius. The size of the explosion is dependent on the current power level of the primary weapon, and the device can only be deployed once the power meter is at level 3 or higher.