Touhou - Danmaku Kekkai (Doujinshi)

[MangaDex]

 

[ZuuIk]

This oneshot is listed as untitled in most places, however it is given a title, Danmaku Barrier, in HD整理, in which a lot of Chado works were compiled long after the Gaku Gaku scans and many of the data entries for the title were made.

This is just in case you were curious about inconsistencies in naming.