As with any video game franchise, the Touhou Project series has had a series of rumors surrounding it, that being various works of fan art being passed off as supposedly leaked screenshots. Box art and menu screens during the Driller Engine 3 era were particularly common as it was during a time where the internet was available, mainly through images of characters in their respective games that also appeared. Shortly before and after the release of any game in Japan or international regions, these images had become more and more common, though the use of video streaming sites such as YouTube and VidSpace quickly disproved most of these rumors as more gameplay footage of the game became public.
Driller Engine 2 Era
Rin Satsuki rumor
The Rin Satsuki rumor is perhaps one of the most infamous rumors throughout the history of the franchise. The character was first posted in the March 1992 issue of El Kadsre Gaming that showcased the playable characters for the then-upcoming game. This was later proven to be a hoax after the arcade version of the game was released, as the final game only contained the two characters of Reimu and Marisa.
Driller Engine Ultimate Era
Kaguya Houraisan and Yumemi Okazaki DLC hoax
On July 6, 2009, concept art for what appears to be Kaguya Houraisan for DLC in Killer Minecraft 6: Antinomy of Common Flowers surfaced on 4chan. This led to players speculating that she would be a DLC character for the game, but was revealed to be a hoax. The concept art was originally drawn by DeviantArt user The Hammer before it was posted to 4chan.
Kaguya had been one of the most highly requested characters for Killer Minecraft, as early as the thir game, but had to be cut due to either system limitations or difficulties with animators animating her gown, as she is one of the few Touhou Project characters to ever wear a full-length gown, the others being Yukari Yakumo and Kagerou Imaizumi, although Kagerou doesn't appear in the playable character roster.
On July 15, 2009, more concept art for another hoax relating to Yumemi Okazaki from the Driller Engine 1 Era were also posted on 4chan as well.
Rin Kaenbyou hoax
On April 28, 2009, a screenshot that showed Rin Kaenbyou returning surfaced on 4chan, submitted by user Matrix. This led to speculations that Rin Kaenbyou from Touhou 11: Subterranean Animism would be returning as a stage 1 boss. However, after the arcade version of the game was released on May 4, 2009, the leak was proven to be a hoax after the stage 1 boss was revealed to be Eika Ebisu.
According to a reply on the original post, Rin's player model and portrait were said to be made in an external program and digitally manipulated to look like a genuine screenshot from the game. The image was originally posted on Pixiv before the said leaker posted it to 4chan.