I.J.A. Tank Mech “I-GA” 4-leg Type

The E-75 Heavy Mech Type G is a first-generation heavy combat mech, developed in 1943 as an experimental alternative to conventional armored vehicles. As one of the earliest mechanized war machines, it was designed to integrate traditional tank components with bipedal mobility, creating a new class of battlefield units. The Type G represents the final standardized iteration of the series, featuring improved turret protection and a more ballistic-resistant design.

Development and Design

The Type G was part of a broader heavy mech development program, initiated to create an assault unit capable of overcoming battlefield obstacles that traditional tanks could not. Since mech technology was still in its infancy, the design heavily relied on existing tank components, such as its engine, armor plating, and primary weapons. The bipedal hydraulic system was introduced to enhance mobility in urban warfare and rough terrain, though it required extensive mechanical upkeep.

The Type G featured a 128mm high-velocity cannon, an evolution of battle-proven tank destroyer guns, allowing it to engage heavy armor and fortified positions. For defensive firepower, it was equipped with dual 30mm autocannons, mounted on the torso to counter enemy infantry and light vehicles.

One of the key refinements of the Type G was its revised turret design, which incorporated a more ballistic-resistant shape, reducing weak points and improving crew survivability. This made it the most durable version of the E-75 series, balancing firepower, protection, and battlefield adaptability.

First Combat Deployment (1943)

The E-75 Heavy Mech series saw its first combat deployment in 1943, achieving immediate battlefield success. In its debut engagement, a single unit recorded 10 confirmed kills, effectively neutralizing enemy tanks and defensive positions while withstanding significant counterfire.

The mech’s high-caliber weaponry and superior mobility over rough terrain allowed it to dominate traditional armored formations, proving the viability of bipedal combat vehicles. Following its battlefield success, the production of E-75 units increased rapidly, leading to the manufacture of over 2,000 units throughout the war.

The Type G emerged as the final and most refined variant, incorporating improved turret armor and a streamlined production process, making it the most widely deployed version of the series.

Operational Role

Designed for frontline assaults and defensive operations, the E-75 Heavy Mech Type G was often deployed as a breakthrough unit, capable of leading offensives and holding key strategic positions. Compared to traditional tanks, its bipedal design allowed it to:

• Navigate difficult terrain more effectively
• Engage from elevated positions
• Reposition faster in urban warfare

Its heavy frontal armor enabled it to withstand anti-tank fire, while its modular turret configuration allowed for battlefield-specific weapon loadouts. However, its mechanical complexity required specialized crews and maintenance teams, making logistics a challenge despite its effectiveness in combat.

Power and Mobility

The Type G is powered by a 1,200-horsepower engine, adapted from existing tank powerplants. This allows it to reach a top speed of 45 km/h, making it relatively mobile for its weight class. Its bipedal hydraulic system, though mechanically complex, provides better adaptability in urban and rugged environments, where traditional tanks would struggle.

Crew and Protection

Unlike later mechanized designs, the E-75 Heavy Mech Type G required a five-person crew, similar to conventional heavy tanks. The crew members include:

• Commander – Oversees battlefield operations
• Gunner – Controls the primary weapon system
• Driver – Manages movement and positioning
• Secondary Gunner – Operates defensive weaponry
• Engineer/Operator – Monitors mechanical systems and assists with in-field repairs

The armor protection is among the strongest of its time, featuring a 180mm-thick frontal plate and additional reactive armor layers, allowing it to endure direct hits from enemy anti-tank weaponry. The Type G variant introduced a redesigned turret shape, improving its ballistic resistance and reducing vulnerability to anti-mech fire.

Specifications

• Weight: 65-70 tons
• Crew: 5 (Commander, Gunner, Driver, Secondary Gunner, Engineer/Operator)
• Armor: 180mm sloped frontal armor + reactive armor plating
• Primary Armament: 128mm high-velocity cannon
• Secondary Armament: Dual 30mm autocannons
• Modular Turret Configurations: Multiple options for battlefield adaptation
• Power System: 1,200 hp engine adapted from heavy tank designs
• Maximum Speed: 45 km/h
• Mobility System: Bipedal hydraulic leg system for all-terrain adaptability
• Maneuverability: Optimized for breakthrough assaults and urban warfare
• Production Quantity: Over 2,000 units in total, with Type G as the final standardized model