Japanese Yukishio class Nuclear Fast Attack Submarine:

From the almost complete destruction of the Imperial Japanese Navy under the might of the American Navy, the Japanese Navy grew to one of the largest and most effective navies on the planet. For a long time, the Japanese navy was labeled Japanese Maritime Self Defense Force but that label was later thrown off. The Japanese navy contended with a number of threats including the Chinese navy and the rebirth of the Soviet navy.

While all of their submarine designs before the Wakashio class had been conventional, the Japanese had among the largest submarine forces in the world. The Imperial Japanese Navy had already been innovative and the Japanese navy had continued that innovation. Many of their submarines were among the most advanced designs in the world. The Japanese navy was an early adopted of the teardrop shaped hull with the Uzushio class submarine in the Nineteen-Sixties.

Tensions had continued to build with the Chinese navy expanding further and the Soviet Union becoming more and more of a threat. As a result, there was pressure to further expand the Japanese submarine force. It was decided to develop a much larger and heavier armed submarine, something more comparable to the American fast attack submarines. The end result was the Yukishio class submarine.

Initial plans were for twelve of these submarines to be built with the number later increased to twenty boats. The first boat was laid down early in the Twenty-Nineties. By the time of the Great Cataclysm, four boats had been completed and a fifth boat was fitting out. The remaining boats were either in earlier stages of construction or had not yet been laid down.

When the Great Cataclysm occurred, two of the boats were deployed while the other two were in port in Kure. One of the two boats later joined up with the New Navy while the two boats that were in Kure and were brought forward in time. As far as the final boat that had been on operations, the submarine appears to have simply disappeared. It is believed by the New Navy to have been destroyed but there is a remote possibility that it could have survived.

The boat that joined up with the New Navy has had its crew long amalgamated with New Navy personnel. Unlike many other non-American designs, the submarine is not generally used as a training vessel. In capabilities, it is generally considered somewhere between that of the Tigershark and Swordfish classes. As with the surviving Wakashio class in New Navy service, the New Navy would likely be willing to return the submarine if the two forces were to develop diplomatic ties with each other.

As far as the two vessels in Kure, one of the boats had only recently commissioned and had been still in the process of properly working up. The other however had actually be in the process of undocking when the Great Cataclysm occurred. If it had deployed a few hours earlier, it would not have been caught with the rest of Kure. Possibly the submarine would have been destroyed but it is also possible that it might have joined up with the New Navy as her sister did.

As one might expect, these submarines remain an important aspect of the Republic of Japan navy. Recently there has been discussion of building additional submarines. Considered state of the art just before the coming of the Great Cataclysm, the Yukishio design is quite likely to form a basis for this design. In fact, the Yukishio class can be considered one of the most advanced submarine designs with only Triax and the New navy matching the submarine’s technology.

The descent from previous designs is clearly evident in the Yukishio design. It used an “X” type tail fins similar to previous submarines starting with the Soryu class. Also in common with previous designs, the Yukishio had a teardrop shaped hull. Through the use of improved alloys and composites, maximum diving depth was improved to 2,500 meters.

Compared to the fusion plant on the Wakashio class, the fusion plant on the Yukishio class produces far greater power, increasing top speed to forty knots. Even though faster, the amount of noise that the submarine produced at lower speeds was decreased to even lower than the Wakashio class. Features of the submarine included a pump jet using electrical power transmission, improved machinery isolation, and a better sound absorbing rubber coating.

While German sonar systems were marginally better in some cases, the Japanese government preferred to support industry whenever possible. Japanese sonar technology had already been considered good but had also improved further. Compared to the Wakashio class, the sonar systems aboard the Yukishio have both greater range and tracking ability.

As with the Wakashio class, the Yukishio class had six forward firing torpedo tubes. Torpedo load out was improved however with thirty-six torpedoes carried for reloads instead of thirty. A more major change was replacing the cruise missile tubes with a pair of long range missile batteries. These vastly increased the number of missiles available. While cruise missiles have greater range than long range missiles, in practice rarely were targets engaged as such extended ranges anyway. Finally, the submarine was armed with a single blue-green laser.

Even though the Yukishio class was a fair amount larger than the Wakashio class, the boat was designed to be operated by a crew not much larger than the older boat. As with the Wakashio class, the new submarine was designed to be able to carry a small special forces compliment. However, the special forces compliment was increased and it was expected that these boats would carry embarked troops more often than the older boats.

Author Note: With respect to time line, these designs may or may not reflect our modern time line. The time line of these writeups diverged from our time line starting around 1999. Consider the universe that these designs are created for to be an alternate universe not bound by ours.

Model Type: SS-682 Yukishio class.

Class: Ocean, Fast Attack Submarine.

Crew: 65; 9 Officers, 9 chief petty officers, and 47 enlisted (Has a high degree of automation.)

Troop Capacity: 12 (Special Forces personnel.)

Robots, Power Armors, and Vehicles:


M.D.C. by Location:


533 mm (21 inch) Torpedo Tubes (6, bow / sides of submarine):

120 each.


Long Range Vertical Launch Missile Batteries (2, forward of sail):

250 each.


Retractable Blue-Green Laser Cannon Turret (1, forward of sail):



Main Sail:



[1] Bow Planes (2):

200 each.


[2] Pump Jet Propulsor (1):



[3] Main Body:



[1] Destroying the submarine’s bow planes will reduce the submarine’s ability to change depths but will not eliminate it. It also makes it difficult for the submarine’s crew to control the submarine giving a penalty of -25% to all underwater piloting rolls.

[2] Destroying the submarine’s pump jet propulsor causes serious problems. The submarine will no longer be able to use forward momentum and the bow planes to keep the submarine level. It is recommended that ballast tanks are immediately blown so submarine comes to the surface.

[3] Depleting the M.D.C. of the main body destroys the submarine’s structural integrity, causing it to sink. If the submarine is underwater, the entire crew will die unless protected by environmental armors that can withstand the pressure that the submarine is under. If on the surface, there are enough flotation devices and inflatable life rafts to accommodate everyone aboard.


Surface: 23.0 mph (20 knots/ 37.1 kph).

Underwater: 46.03 mph (40 knots / 74.07 kph).

Maximum Depth: 8,202 feet (2,500 meters).

Range: Effectively Unlimited due to fusion engines (needs to refuel every 20 years and requires maintenance as well). Boat carries six (6) months of supplies on board.

Statistical Data:

Length:  349.41 feet (106.50 meters).

Beam:    38.88 feet (11.85 meters).

Draft:    30.84 feet (9.40 meters).

Displacement: 5,120 tons surfaced and 5,950 tons submerged.

Cargo: Submarine is very cramped, 12 tons (10.88 metric tons) of nonessential equipment and supplies. Each enlisted crew member has a small locker for personal items and uniforms. Boat’s officers have a bit more space for personal items although still extremely cramped. Most of the boat’s spaces are taken up by extra torpedoes, weapons, and engines.

Power System: Nuclear fusion; average energy life of 20 years. Normally refuels every 15 years.

Black Market Cost: Not for sale; many nations and organizations would pay hundreds of millions of credits for a new and undamaged Yukishio class Submarine.

Weapon Systems:

  1. One (1) Retractable Blue Green Laser Cannon Mounts: This cannon is mounted in front of the main sail and fully retractable under concealing deck plates so that they do not disrupt water flow at high speeds. They are considered useful both underwater and on the surface. As a blue-green laser, they have a greater range underwater than they would otherwise. The weapon system is used mainly as close defense against torpedoes underwater and against aircraft when on the surface.

    Maximum Effective Range: In Atmosphere: 2 miles (3.2 km). Under Water: 1 mile (1.6 km).

    Mega-Damage: Cannon inflicts 2D4x10 M.D.C. per blast.

    Rate of Fire: Four (4) attacks per melee round.

    Payload: Effectively Unlimited.

  2. Six (6) 533 mm Heavy Torpedo Tubes: On the sides of the submarine are six torpedo tubes. Tubes are 21 inches (533 mm) wide and torpedoes can be used against both surface ships and submarines. Torpedo launchers have a special automated reloading system to reduce noise. For warheads, heavy torpedoes should be treated as having long range missile warheads. Along with standard torpedoes, the launcher can also fire missiles (long range or cruise missiles) in special canisters and rocket boosted ASW torpedoes. Submarine carries thirty-six reloads for torpedoes (in addition to six heavy torpedoes in the tubes) and can carry up to seventy-two mines in place of torpedoes.

    Maximum Effective Range: 40 miles (34.8 nautical miles / 64 km) for torpedoes.

    Mega-Damage: By heavy torpedo warhead type (See revised Rifts torpedoes for details), can fire missiles (long range or cruise missiles) in special canisters as well (See revised bomb and missile tables for details.)

    Rate of Fire: Can fire heavy torpedoes one at a time or in volleys of two (2), three (3), four (4), or six (6) heavy torpedoes. Reloading takes one full melee round.

    Payload: Six (6) heavy torpedoes total [Has thirty-six (36) additional heavy torpedoes for reloads.]

  3. Two (2) Long Range Vertical Launch Missile Batteries: A pair of launcher is in front of the main sail. As with similar cruise missile batteries, the long range missile batteries are located outside of the pressure hull. While developed mainly to engage surface and land targets, the system is also effective at engaging aircraft. Anti-Submarine rocket launched torpedoes also can be fired from the launchers (See revised Rifts torpedoes for details.) Designed to be able to engage one than one target at the same time. Long range missile batteries can be used on the surface or fired while the submarine is underwater with a maximum depth of around 150 feet (45.7 meters.)

    Maximum Effective Range: As per long range missile type (See revised bomb and missile tables for details.)

    Mega-Damage: As per long range missile type (See revised bomb and missile tables for details.)

    Rate of Fire: Can fire long range missiles one at a time or volleys of two (2), four (4), or eight (8) long range missiles per launcher per melee round. Maximum total between launchers is sixteen (16) long range missiles per melee round and can be fired at multiple target at the same time.

    Payload: Thirty-two (32) long range missiles per launcher for a total of sixty-four (64) long range missiles.

  4. Six (6) Advanced Decoys: The submarine carries four advanced decoy drones. They are a small automated vehicles that creates a false sonar image designed to mimic the submarine’s sonar signature. It has a small propulsion system that can simulate movement [has a maximum speed of 23.0 mph (20 knots / 37.0 kph)] and maneuvers. In addition to be able to be used to decoy torpedoes, they can sometimes be used to trick another vessel while the submarine moves into position. If decoys are not destroyed, they can usually be recovered and repaired if they can be retrieved. Rifts Earth decoys systems are assumed to not be effective against Phase World / Three Galaxies guidance and targeting systems due to technological differences.

    M.D.C.: 20.

    Range: Not applicable. Decoys do however have a duration of 30 minutes (120 melee rounds) once launched.

    Effects: The decoy has an 80% chance of fooling ordinary non military sonars and non smart guided torpedoes, the decoy has a 50% chance of fooling military level sonars (like those of the Coalition) and non “smart” torpedoes, and the decoy has a 25% chance of fooling advanced military sonars (Like those of the New Navy and Triax) and “smart” torpedoes.

    Rate of Fire: Boat can launch one decoy drone per melee round.

    Payload: Four (4) decoy drones.

  5. Noisemakers: The submarine carries noisemakers in order to decoy torpedoes. They are most effective against normal torpedoes and less effective against “smart” torpedoes. Considered in many ways to be the last line of defense against incoming torpedoes and similar systems are carried on most submarines. The noisemakers are launched from the middle of the submarine.

    Effects: 50% of decoying normal torpedoes and 20% of decoying smart torpedoes.

    Rate of Fire: Two (2) noisemakers at a time (Can be reloaded in one melee round).

    Payload: Twenty (20) noisemakers.

Special Systems:

The submarine has all systems standard on a robot vehicle plus the following special features:

[ Altarain TM, Bandito Arms TM, Brodkil TM, Chipwell Armaments TM, Coalition States TM, Cyber-Knight TM, Federation of Magic TM, Free Quebec TM, Golden Age Weaponsmiths TM, Horune TM, Iron Heart Armaments TM, Kankoran TM, Kittani TM, Kydian TM, Larsen’s Brigade TM, M.D.C. TM, Mechanoids TM, Mega-Damage TM, Megaversal Legion TM, Millennium Tree TM, Mutants in Orbit TM, Naruni Enterprises TM, Naut’Yll, New Navy TM, New Sovietskiy TM, NGR TM, Nog Heng TM, Northern Gun TM, Phase World TM, Psyscape TM, Rifter TM, SAMAS TM, S.D.C. TM, Shemarrian TM, Splugorth TM, Stormspire TM, Sunaj TM, Tolkeen TM, Triax TM, Wellington Industries TM, Wilk’s Laser Technologies TM, Xiticix TM, and Zaayr TM are trademarks owned by Kevin Siembieda and Palladium Books Inc. ]

[ Beyond the Supernatural®, Heroes Unlimited®, Nightbane®, Ninjas & Superspies®, Palladium Fantasy®, and Rifts® are registered trademarks owned by Kevin Siembieda and Palladium Books Inc. ]

Writeup by Kitsune (E-Mail Kitsune).

Copyright © 2018, Kitsune. All rights reserved.