Niy did two Sekibanki doujin, which this is the first of. I'd like to typeset the second one too.
This was translated on Danbooru by Levander of DB Scans, without whom the western Touhou fanbase would be a much darker place.
Danbooru: https://danbooru.donmai.us/pools/13328
Raws: https://e-hentai.org/g/781305/5a46adb9a5/
Niy's rapidly becoming one of my favourites.
If you liked this doujin, please support the artist behind it:

Niy's twitter: https://twitter.com/Niy_Koubou
Niy's Pixiv: https://www.pixiv.net/en/users/165186
Niy's Melonbooks: https://www.melonbooks.co.jp/circle/index.php?circle_id=27365

5 stars hot damn!

Base +6