The Principle Wall is the boss of Stage 6.1 in R-Type Final 2.

Bydo Lab

• Subtitle: Grave keeper
• Enemy Size/Strength: Huge Bydo
• Enemy Classification 1: Mecha Species
• Enemy Classification 2: Airborne
• HP: ****
• Stage: Unknown Underground Ruins

Strategy

The Principle Wall must be defeated by destroying both of its arms. Its attacks include:

• Firing laser beams from the cannons on its arms and its head.
• Throwing bombs from its arms. The bomb scatters in 5 directions like the * symbol when destroyed/exploded.

As long as its arm on the left side is present, it may occasionally rotates anticlockwise. During this situation the Force should be positioned on the fighter's back to continue damaging it.

When the Principle Wall is destroyed in the Main Stage Course, the player's fighter will be enveloped by a mysterious aura, transforming into a B-1D Bydo System Alpha, for reasons unknown.

Trivia

• Defeating the Nomemayer in R-Type Final also results in the pilot's ship turning into a Bydo System Alpha.
  • As well, given they're both atypical entities capable of generating geometric defences, and transform the player into a bydo, it could be said the two reseble eachother.
• Due to the current lack of detailed descriptions in the Bydo Lab, the meaning of its name, and which principles it's guarding/upholding are unknown.
  • Taking the subtitle of "Grave Keeper" into account, though, one can assume it may embody the honour of the dead. Seeing as how only R craft wrecks are present in the background, however, it is unknown who/what's grave it's guarding.

Gallery