Digitalscape
TODO: read through a bunch of Japanese sources about this company and document it better.
Digitalscape Co., Ltd., or DIGITALSCAPE Co., Ltd., is a Japanese company involved with the development of Super Mario Galaxy and possibly Super Mario Galaxy 2.
Credits
"DIGITALSCAPE Co., Ltd." is listed in the "SPECIAL THANKS" section of both games' credits.
Being credited in Super Mario Galaxy 2 does not necessarily mean that they were involved with its development; they may only be credited for their work in Super Mario Galaxy 1 that was retained in the second game.
Copyright registration
"Digitalscape Co., Ltd." is listed in the United States Copyright Office registration of the Super Mario Galaxy 1 Japan release: https://publicrecords.copyright.gov/detailed-record/23581903
There, they are listed as the author of "Visual work" (as opposed to Nintendo, who is listed as the author of "Audiovisual work, Computer program").