It seems to look like we won’t be getting any SSSS.GRIDMAN doujins anymore as Melonbooks (a popular doujin retailer in Japan) has officially pulled all its stocks related to the series. This was confirmed in a statement that the official website posted on Tuesday.
This action was due to the franchise’s new guidelines when it comes to derivative works (e.g. doujinshi) that was posted on its official website on November 1. Which means anybody that creates or publishes SSSS.Gridman-related fan works that do not go by the company’s guidelines are considered as a violation of copyright.
To give you an idea of what the guidelines are, fans are prohibited to copy or trace any image, video, writing, or music from the SSSS.Gridman anime. In relation to the selling of related works, the guidelines are vague. It only says that the staff will intervene and ban the related sales if they are “exceeding the bounds of doujin activity.”
Doujins are one of the most popular fan work sold in Japan especially in big events in like Comiket. Although these are technically a copyright violation to sell these kinds of works, publishers and official companies rarely take actions on them.