
Originally Posted by
Comun
Hibiki and Chikagi have been interacting with Fsn and Tsukihime character since their debut. Hibiki is a creation of Caubac, a Tsukihime-adjacent character mentioned a few times over there and featured FsF. They are and have always been unquestionably part of the Type-Moon franchise.
Canaan is written by Nasu but it's a spin-off of a whole other company's franchise.
Fire Girl is built on magic and interplanetary exploration mechanics that have nothing to do with how TM does magecraft. April Fools 2013 even has a joke with Honoka overpowering the heroine because she doesn't have magical energy as a finite resource in her home series.
Zvezda I know nothing concrete about it, but like Fire Girl, it's another independent Meteo project that nothing to do with any Nasu series.
DDD is a thing that Nasu wanted to be part of Type-Moon at some point then gave up and pasted a disclaimer in the TM website saying it doesn't connect to his other titles in any way. Magecraft is never featured in DDD's stories. But DDD's case is interesting because the series is referenced a couple times in KnK spin-offs. First, Mirai Fukuin has Mitsuru stealing a pseudonym from a manga he liked and this pseudonym happening to be the name of a DDD character. And second is Shuumatsu Rokuon, which is about the KnK girls being trapped inside the plots of various movies because of a magic project, and one of them mentions Kanata from DDD. So, ultimately, it seems pretty clear that DDD does exist in the Nasuverse, but as an in-universe manga that got a movie adaptation. Probably made by the in-universe versions of Nasu and Takeuchi since they can't be writing the Nasuverse titles inside the Nasuverse.