Stage: Southeast Asia Ruins
Described as an "ancient weapon" in the Sonic Wings 3 strategy guide, Mars-Vesta is a shape-shifting boss capable of altering its form. The translation of its name マルス-ヴェスタ (literally marusu-vesuta) as "Mars-Vesta" is possibly incorrect. However, so far no other translation for the name has been found, and the use of "Mars" in its name is probably a reference to its inspiration, detailed below.
Mars-Vesta seems to be a parody of the "Martian Ultimate Weapon" featured in the anime series Space Adventure Cobra. The weapon appears in episode 12, "Amazing: The Ultimate Weapon." The ultimate weapon is an egg-shaped item found in a chest of treasure and described in the third volume of the "Mars Ancient History Texts." Like Mars-Vesta, the ultimate weapon has a single eye; however, this eye is green with eyelashes. The weapon seems innocent at first, but it has the ability to evolve: the ultimate weapon will become a stronger version of any weapon its eye sees. During the episode, the weapon evolves into a sword, a gun, and finally a tank. The Mars Ancient History Texts states that if the weapon is allowed to evolve to its final form, it will "duplicate the entire universe." In the anime, when the weapon is ultimately defeated in its tank form, it cannot be destroyed; instead it reverts to its inert egg form.
Mars-Vesta first appears early in the stage in the form of Fire Master. If Fire Master is not defeated, Mars-Vesta escapes deeper into the stage while still in the guise of Fire Master; otherwise, it escapes in its true form resembling a small, egg-shaped rock with a vertical red eye. At the end of the stage, Mars-Vesta bursts from a temple and appears briefly in its true form, first as the small rock then as a much larger one, before taking on another shape.
Its most common behavior is to mimic the player's aircraft; in two-player mode, Mars-Vesta appears as doppelgangers of both aircraft at once. These copies are enlarged, pixelated, grey-scale sprites of the player's plane. The doppelgangers will then attack with fireballs in a pattern according to which pilot the player is using. However, Mars-Vesta may also take the shape of one of three enemies: a small tower from the Tokyo level of Sonic Wings 2, the Pomornik, or Manbou. These shapes are not enlarged and pixelated as with the aircraft, but they do appear in grey-scale. As the tower, Mars-Vesta is virtually harmless; just like its Sonic Wings 2 counterpart, it falls over backwards and defeats itself. As the Pomornik, Mars-Vesta attacks normally. If it appears as Manbou, it does so briefly; however, unlike the real Manbou, it attacks the player with a few fireballs. No matter which form Mars-Vesta takes, a checkered plane appears after it is defeated, allowing the player to choose the game's final stage.
In its true form, Mars-Vesta continues the eye motif seen in many bosses in Sonic Wings 3. However, this may only be in homage to the Martian Ultimate Weapon and may not signal that Mars-Vesta is related to the other bosses.