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Hoshioka (ホシオカ) is an engineering factory located in the Principality of Zeon's Side 3. The company was an occasional subcontractor of Zeonic, eventually tasked by the company with developing a Prototype MS for the Principality of Zeon in U.C.0074 ostensibly as a new 'mobile worker'. The factory features prominently in Developers: Mobile Suit Gundam Before One Year War.


Before the onset of Mobile Suit technology, Hoshioka mostly focused on producing industrial machinery for civilian use, likely in part the assembly of Mobile Workers. One of several subcontractors used by the much larger Zeonic Company, the civilian manufacturing company was tasked in UC 0074 to develop a new Mobile Suit prototype. The small factory was responsible for the development of one version of the MS-04 Prototype Zaku design, specifically one housing an internal nuclear reactor as the power source. Hoshioka's head workers quickly deduced that although viable alternative power sources were available, and were indeed being worked on by Zeonic's headquarters, Hoshioka was brought in due to their concern of a possible nuclear meltdown if the project was conducted on their own premises.

Over the course of their work on the prototype, the Hoshioka engineers encountered and overcame a number of challenges to Mobile Suit development, and their strides in advancing the early stages of the technology informed and influenced the future of mobile technology throughout the Universal Century. Upon completing their prototype and outperforming other test units at a company product demonstration Zeonic held, attended by several high-ranking military officers, Hoshioka would be put into full-time Zaku component production, with the parent company pushing for an output of 50 units a month across their facilities and their competitors who had acquired production licenses from the Principality. However, faults with this partnership were common, it not being unusual for the main Zeonic factory line to break down and forcing Hoshioka to pick up the slack.


  • Mion Hoshioka - Daughter of Genzaburou Hoshioka, Mion often acts as an on-site work foreman in the absence of her father. She is also the main test pilot of the prototype design, with her competitive streak pushing her to excel in handling the new technology. Her familiarity with the Hoshioka workforce's idiosyncrasies allows her to influence their attitudes towards taking the MS development contract.
  • Genzaburou Hoshioka - Chief of the Hoshioka industrial factory, Genzaburou is a coarse but experienced engineer, whose skill and judgement have gained him the faith and loyalty of his workforce. He is known to frequently use of folksy proverbs, often prefacing them with "Like we say back home", implying he is not native to Side 3.
  • Yasu Nishikawa - A leading mechanic at Hoshioka, Yasu is considered by his coworkers to be exceptionally clever. He has a great interest in tinkering with the design of the Mobile Suit after seeing the CG blueprints brought to the factory by Theo. As with many other Hoshioka workers, when out of company clothes, his style of clothing is reminiscent of a Yakuza thug.
  • Three Old Men - A trio of aging mechanical engineers, they have both impressive experience and unique talents that make them indispensable. The only named Old Man, Miguel, is the sole employee of Hoshioka capable of angstrom-grade mechanical alterations. His skill even impressing Zeonic HQ engineers, Miguel will occasionally refuse to work unless he is given tea or sweets. The other two are seen playing a card game to pass the time, seemingly based on fantasy trading card games like Magic the Gathering.
  • Auntie - While her specific role in the company is uncertain, she appears to work out of the factory office and has access to the company president's scheduling. Auntie is shown to have good common sense and an ability to read other people well. It is she who offers the simplest and easiest method to overcome Minovsky Particles interfering with inter-factory communication. She suffers from the vice of illegally-imported snack foods.
  • Theo Pajitonov - A supervisor to the MS project subcontracted to Hoshioka. Sent by Zeonic Company's headquarters to oversee the progress of the industrial factory's prototype design. While he does not actually work for Hoshioka, his close working relationship with Hoshioka endears the offbeat employee force to him, to the point of defending their quirks and decisions to his superiors.
  • Watch Dog - An unnamed dog present at the factory, often found at the security hut outside of the factory. By appearance, it bears similarity to an Afghan hound.



  • ZI-XA3 'Crabman' Mobile Worker variant
  • ZAS nuclear reactors
  • Gramonica monitors
  • Motorcycle
  • Gantry cranes
  • Samson Flatbed Trucks


A number of important manufacturing firsts are spearheaded in Mobile Suit development by the Hoshioka team. Among these are:

  • Internal reactor power
  • Motion-capture movement input
  • Concept of main propulsion unit as a removable 'backpack'



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