Tenkou Spellship

Unused Cannon
The game data displays that this ship has a secondary cannon, but the Tenkou Spellship never uses this cannon, causing the name of this cannon to be unknown. Judging by the game data, a cannon called the Fire Arrow is right next to and precedes the Houroku Torpedo in the list of cannon names, so it's possible the Fire Arrow was initially programmed as an intended cannon but was scrapped.