Evil Eye Σ
The Evil Eye Sigma (Σ) (イビルアイ∑ ibiruai sigma) is a flying tank created by Rika. It was used on the Extra Stage of Story of Eastern Wonderland to fight Reimu Hakurei and Genji, where it moved left and right, shooting bizarre danmaku at the player. Rika again thought it was enough to defeat Reimu compared to her Flower-Tank, but was again defeated, causing a huge explosion for the player to dodge. With the Evil Eye Σ, Rika also created the Shrine Tank, the Flower-Tank, the bakebake, some shining objects and a few cannons.
There was a known "flying tank" called the Antonov A-40 that was created by the USSR, which was an attempt to allow a tank to glide onto a battlefield after being towed aloft by an aeroplane, to support airborne forces. There was also the prototype Special Number 3 Light Tank Ku-Ro (特三号戦車 クロ) that was also designed to be a flying tank during the Japanese Empire. Additionally, the AH-64 Apache is often referred to as a "flying tank" due to its weaponry.
Evil Eye (イビルアイ ibiruai) is likely referencing the typical "evil eye" that's known in many cultures, which is believed to cause injury or misfortune for the person at whom it's directed for reasons of envy or dislike. It also shares its name with YuugenMagan's title: "EvilEye".
It appears to have one big eye with a red iris and black eyelids. It has two large purple wings, a halo, and two large tentacles. Below there is something green (leaves?). On the lower eyelid, there is a red Sigma (∑), the eighteenth letter of the Greek alphabet that's the equivalent to the Latin letter "S", which is also shown in its name. The tank's motif bares a strong resemblance to the Evil Eye.
- The Evil Eye Σ, along with Rika, was the first Extra stage boss ever in a Touhou Project shooting game.
- Reimu Hakurei and Rika talked about Rika been a Stage 1 boss in the Extra stage of Story of Eastern Wonderland, while stating that if Reimu followed Rika during Stage 1, then Reimu's battle with the Evil Eye Σ would've been Stage 2. This is breaking the fourth wall.