This pool is for images dedicated in memory of Virtual YouTubers who have retired. When adding to the pool, it should be made clear by either the creation date, content, or commentary that the image was made specifically in honor of their graduation.
Keep in mind that this pool isn't exclusive to YouTubers, and should also be used for streamers from other sites, such as Bilibili, Niconico, TwitCasting, Twitch.tv, and so forth as well.