Phantasy Star Gaiden on Game Gear: The Side-Story Sega Never Took West

Phantasy Star Gaiden — ファンタシースター外伝, literally “Phantasy Star Side-Story” — went on sale in Japan on 16 October 1992 as a Game Gear cartridge, priced at 4,500円 before tax. It carries the Phantasy Star name, but almost nothing else from the series: no spaceships, no planet-hopping science fiction, no numbered chapter. Sega handed the handheld side-story to an outside subcontractor, and the result is a medieval fantasy RPG that critics in Japan did not care for at the time and that never saw a release outside Japan.

• Japanese title: ファンタシースター外伝. Developed by Japan System Supply, a subcontractor Sega brought in rather than an in-house team; published by Sega
• Game Gear cartridge: 16 October 1992 · 4,500円 before tax · role-playing game
• Catalogue number: G-3405, from Sega’s own software list. The Media Arts Database row (M755138) has no product code at all; Kataban added it on 13 October 2026, so G-3405 finds the cartridge here
• Where it sits in the series: the seventh Phantasy Star-branded release, and a spin-off rather than a numbered entry. Unlike the previous handheld game, Phantasy Star Adventure (an adventure game), this one was built as a full RPG — just not a very well-received one
• Japan only: no North American or European release. A fan translation exists, made by a group called Magic Destiny; a more literal translation of the script is hosted separately, since the fan patch is reported to change parts of the story
• Buying it: search the full title ファンタシースター外伝 at both shops. On 21 September 2026 Suruga-ya had one copy in stock at ￥17,200, with marketplace copies from ￥7,990

What is Phantasy Star Gaiden, and how does it fit the series?

By 1992 Phantasy Star was three console RPGs deep — science-fantasy adventures across a solar system, with spaceships, androids and a plot that ran across all three games. Sega’s handheld spin-offs told a different kind of story. The first, Phantasy Star Adventure, was a text adventure. Phantasy Star Gaiden was pitched as the real thing: a proper RPG, built for the Game Gear, and the seventh release to carry the Phantasy Star name.

What it delivers is a medieval fantasy story with almost no connection to the series it is named after. Play centers on two characters, アレック (Alec) and ミナ (Mina), who set out to rescue Alec’s father from a group of bandits called ダイダロス (Daidaros). The setting is a colony where a demon named カブロン (Kabron), sealed away four hundred years earlier, is trying to return. None of it involves the science-fiction trappings — the spaceships, the androids, the planets Palma, Motavia and Dezoris — that define the mainline games.

Japanese reviewers were not kind to it. Famitsu’s Cross Review panel gave it 18 out of 40 — a poor score — and retrospective write-ups single out two problems: an unusually high random-encounter rate against very small groups of enemies (often just one or two at a time), and a story too short and too thin to build any attachment to its characters. One English-language retrospective calls it a spin-off “with a very thin connection to the main series and almost no science-fiction elements” despite being built as a full RPG rather than the adventure-game format of its predecessor.

It has aged into something else, though: a collector’s curiosity. It is the odd entry out in a series otherwise defined by its science-fiction identity, made by a studio outside Sega’s usual RPG teams, and never patched, remastered or re-released in any form — unlike several other Game Gear Phantasy Star spin-offs.

Which release is the Japanese cartridge, and what is its code?

There is one release. Sega’s own Game Gear software list gives the row for ファンタシースター外伝 as 10月16日, role-playing genre, 4,500円, catalogue number G-3405.

The Media Arts Database carries the cartridge as row M755138, with the title, platform, year and publisher recorded, but no schema:productID and no barcode — the same gap this catalog keeps finding in the government record for Game Gear software. The code G-3405 comes from Sega’s own list, and two secondary sources agree with it: GameFAQs, whose release entry gives G-3405 together with the barcode 4974365134051 — the same barcode printed on the back of the box — and SMS Power!. We found no primary source other than Sega’s list that prints G-3405: the box back carries 671-2246 and the cartridge label 670-2352.

Suruga-ya does not index the cartridge under G-3405. Its own product page uses an internal parts number, 670-2352, instead — the same pattern seen elsewhere in this catalog where Suruga-ya’s in-house numbering does not match Sega’s catalogue codes. The Japanese title is the reliable search term at both shops; the code is not.

What was the list price, and what does it cost now?

Sega’s software list gives 4,500円 before tax. Suruga-ya’s 定価 field on the product page reads ￥4,950 — exactly 4,500円 plus 10% consumption tax, so the two figures agree; nothing here needed to be left out for disagreeing sources.

On 21 September 2026 Suruga-ya had one complete copy in stock at ￥17,200, tax included, plus seventeen marketplace copies starting at ￥7,990. A second listing, box only, was sold out. That puts this cartridge well above the Sega CS5 strategy titles covered elsewhere in this catalog (which run ￥5,000–6,000) and closer to the pricier end of the Game Gear Phantasy Star line — consistent with its reputation as a scarce, sought-after oddity rather than a common cartridge.

Can you buy it today, and which copy should you buy?

Yes, though the in-stock supply is thin. Suruga-ya showed two listings on 21 September 2026:

• ファンタシースター外伝 — complete, in stock at ￥17,200, with seventeen marketplace copies from ￥7,990
• [外箱のみ] ファンタシースター外伝 — outer box only. Sold out, with a marketplace copy at ￥4,480

The bracketed listing is not a game — 外箱のみ means the box alone, a common pattern across this catalog’s Game Gear coverage. On Buyee, the same full title showed results: 10 (this game: 9), copies of the cartridge in various conditions; the rest were unrelated listings that happened to match the search text (on 22 September 2026, a back issue of a PlayStation magazine). Prices as of 22 September 2026: roughly ￥3,500–20,500 for the cartridge. There is no overseas-version problem to filter for — the game was never released outside Japan.

How do you search each shop for it?

Both shops get the same words: the full title, ファンタシースター外伝.

Suruga-ya: on 22 September 2026 the title alone showed results: 2 (this game: 2). Breakdown on 22 September 2026: 1 complete copy, 1 box-only listing. The catalogue code G-3405 and the shop’s own parts number 670-2352 were not tested against the live search here; treat the title as the confirmed route and the codes as unverified for this shop.

Buyee: the full title showed results: 10 (this game: 9), roughly 90% purity on 22 September 2026 — one of the cleaner searches in this series. No platform qualifier was needed.

Why search Kataban for this one?

Because the Japanese title is the only search term that reliably works at the shops, and Kataban is built to take an English-speaking collector straight to that title without needing to type it in kana first. On Kataban itself, the English title Phantasy Star Gaiden finds the cartridge too (checked 13 October 2026), and so does the code G-3405. A cartridge this scarce — one in-stock copy at one shop, on the day we looked — is exactly the kind of listing that is easy to miss without knowing the right Japanese words to search.

Phantasy Star Gaiden · ファンタシースター外伝 · Game Gear, 16 October 1992 (G-3405) · Japan System Supply / Sega

Where to buy: Suruga-ya.jp — the full title (ファンタシースター外伝) · Buyee — the same full title
See it on Kataban →