"Well, space is there, and we're going to climb it, and the moon and the planets are there, and new hopes for knowledge and peace are there. And, therefore, as we set sail we ask God's blessing on the most hazardous and dangerous and greatest adventure on which man has ever embarked."
-President John F. Kennedy, inscribed on Hiryu commissioning plaque
The Hiryu-class enhanced deterrence explorer is an exploratory starship in service with the New Free Planets Alliance Exploratory Division. The first dedicated exploration ship class in the Alliance, the Hiryu-class is the most famous class of explorers in the Exploratory Division and one of the oldest of the ship classes designed by the Free Planets Star Fleet. Despite the age of the design and the heavy modifications from the baseline that have followed, the class remains in production as a squadron leader and flagship for the Independent Exploratory Groups. As with other large explorer classes, ships of the Hiryu-class are named after famous scientists, philsophers, mathemeticians, and artists, although unlike other classes, some are also named after large "majestic" creatures, including Hiryu herself.
The Hiryu-class represents a greater change in role and design throughout the course of its lifetime than any other government-designed ship in service. Hiryu was originally constructed in 1995 CE as the first dedicated exploratory ship in the Star Fleet. Political factors combined with resource shortages had prevented the construction of other dedicated exploratory vessels as reconstruction efforts on Arzor were still ongoing, drawing much of the Alliance's resources away from expansion of the space fleet.
A full five years after the close of the Unification Wars, however, it was decided that the Alliance would be best served by beginning to turn its focus outwards to the rest of the galaxy. To this end, the Hiryu Project was established, to design and construct a dedicated long-range explorer. At the time of her construction, she was by far the largest ship ever built in the Alliance, nearly a full 1/3 longer than the next-largest ship (the Shiva-class heavy battleship) and nearly twice the displacement.
In mid-1996, Hiryu embarked on her first exploratory cruise, departing the Arzor system to chart a relatively close system some 50 lightyears away as a basic shakedown cruise before venturing further into the galaxy. This, however, was not to be, as upon entering the system, Hiryu encountered an unknown crystalline life form that immediately launched an attack on the ship. Despite her strong defenses, Hiryu sustained major damage and heavy casualties, surviving only due to a last minute ramming attack that force the unknown entity to retreat.
The Hiryu Incident, as it would come to be known, resulted in a major shift of priorities within the Alliance government. Expansion of the warship fleet became the top priority to defend against potential attackers, while the exploration budget was slashed. Hiryu herself was towed back to her drydock and left in the care of her builders, as the dock itself was not well-suited to the mass-production of warships the Star Fleet had envisioned.
Hiryu would languish in her drydock for the next decade as the Star Fleet saw voluminous expansion, although her builders continued to tinker with the design based on lessons learned from the Hiryu Incident and the design of additional warships. By 2007, the Reaper-Omega War had ended in a coalition victory and the Alliance government felt confident enough in the strength of the Star Fleet to begin diverting resources back to exploration.
With Hiryu still in drydock and representing a capable hull that could be reused and upgraded, resources were allocated to her complete reconstruction based on her builders' recommendations. The large hull provided ample space for upgrades, while her exterior was extensively modified until she was all but unrecognizable from her previous appearance. By this time she had been eclipsed as the largest starship in Alliance service by the new Kulishuna-class super-capital ship, but was still far larger than the standard battleship, her mass having been increased by some forty percent during the refit.
Hiryu was relaunched later that year to much fanfare, and officially began her second maiden voyage. To represent the major changes to the design, the new ship was redesignated Hiryu Kai, although the class name was unchanged. After an uneventful shakedown, her second voyage led her to encounter a few rogue Omega warships, which she was able to easily dispatch with her upgraded armaments.
Given this success, the Alliance government authorized the creation of a new branch, the Exploratory Division, which would be separate from the Defense Force but still considered a uniformed service of the New Free Planets Alliance. Hiryu Kai would be transferred to this division, and a new fleet would be constructed with a dedicated mission, including additional ships of the Hiryu-class. With the development of more advanced technology, the size of the original Hiryu was no longer required for a deep-space explorer, and instead the Hiryu-class was ordered as a command and limited combat vessel designed to provide the Exploratory Division with enough strength to protect itself from hostile encounters.
The Hiryu-class is distinguished by her enormous size relative to other explorers as well as even most warships, out-massing all warships save the few super-capital ship designs and a few civilian bulk cargo transports. This size is as much due to technological constraints at the time of her design as it is due to her envisioned deep-space exploration role.