Each Episode Is Built Around One New Threat
The six-episode structure is unusually easy to read once you notice the pattern.
Episode 1 revives Dark Schneider. Episode 2 introduces Efreet. Episode 3 resolves Gara. Episode 4 centers Di-Amon. Episode 5 centers Arshes Nei. Episode 6 turns Abigail into the immediate final threat.
How you can tell
The episode titles almost function like a boss list.
Why it matters
The OVA compresses a larger manga arc by making each episode carry one major opponent and one relationship change. That is why transitions can feel abrupt even when the overall direction is clear.
The Ending Stops Abigail, Not the Whole War
SPOILER!
Myth: Episode 6 is a complete ending to BASTARD!!
Episode 6 gives the OVA a real climax, but it does not close the larger conflict.
Dark Schneider returns, the Cyclops is destroyed and Abigail is defeated. Kall-Su is still outside the immediate battle, the larger threat around Anthrasax remains, and the manga story continues far beyond what these six episodes adapt.
Why it matters
The OVA works best as a complete 1990s adaptation of one early movement, not as a substitute for the entire BASTARD!! story.