After two epic opening episodes, the Giant Robo series descended closer to a state of normalcy in its good but not always exceptional third OST. Fortunately Giant Robo IV Original Soundtrack marks a progressive return to the series extremely high standards.

All the Giant Robo soundtracks regularly reprise themes from earlier episodes, but Giant Robo IV does so the most frequently. In fact all but five tracks are at least partial reprises of pre-existing themes. Fortunately the themes chosen for inclusion are mostly superb, and the reprises here are in some cases the definitive versions. The versatile Experts of Justice theme gets its most poignant reprise in "Taiso and Yoshi", while the ominous Big Fire theme takes a slightly more subtle and effective form in "Genya's Ambitions". "The Battle Below Ground" adds a foreboding new intro to episode 1's "Escape", making an already excellent action theme even more dramatic.

The great joy of a couple of the reprises is they establish themes that, though great in their original appearances, weren't necessarily ones you expected to hear expanded upon in later episodes. Who would have thought that episode 1's light-spirited "View from Up High" would get an even more endearing flute and clarinet arrangement to become "Ginrei's Theme". Or that episode 3's fantastically moody, troubadour-like "Paris in Ruins ~Alberto and Ivan~" would receive an equally engaging classical violin solo in "A Heated Battle Among Men (Alberto's Theme)", and establish a surprisingly empathetic theme for the series' main villain in the process.

Of the entirely new themes in episode 4, the sorrowful choral mass "Requiem" makes the most powerful impression. Other entirely new compositions include the atmospheric "Ryozanpaku Laboratory", the call to arms "The Valor!! Shanghai Experts Battle" and its triumphant successor "GR's Revival". Aside from Requiem these themes don't stand out as much as some of their counterparts in other episodes, but they succeed in keeping the narrative flowing strong and swift, a hallmark of Giant Robo soundtracks.

The only questionable part of the score is the 12-minute opening track "String Quartet -Twilight of the Heroes-". It feels more like a tacked-on bonus than an essential part of the score, and it fails to offer memorable thematic material in the vein of the rest of the soundtrack. (A string quartet reprise of Daisaku's theme at the end fits somewhat more naturally with the rest of the score.)

At only 41 minutes the soundtrack is on the short side, and the prevalence of reprises might at first appear a drawback, but anyone who's heard the themes from the first two episodes of Giant Robo will be reeling in delight at the new versions here. As for those who for whatever reason decide to begin their foray into the series midway through, a wealth of powerful thematic material awaits in Giant Robo IV Original Soundtrack.