When you post or re-upload artwork from Pastela to pixiv, the work type is automatically set to "illustration".
You can't change the work type to manga or Ugoira.
The work type also can't be changed when editing artworks that were originally posted from Pastela on pixiv.
If you wish to post under a different category than illustration,
please export the data from Pastela and upload it directly to pixiv.
To learn more on how to export data from Pastela, please see below.
How can I export canvas data?