The creator of Astrea, Tonari no Botulinus, has said farewell on his pixiv account on the 31st of December 2021, and deleted his account at the start of 2022. T_T
A bit later, it came to my attention that he updated "Defeated Warrior" a while after I posted the gallery here. Fortunately, I was able to obtain a copy of the updated version (with 18 added images), and is thus presented here.
Chapters 01-10 can be found here: /g/1237973/cabd12ad7d/ Chapters 11-18 are here: /g/1367149/f3ed4c1919/ Some hack sniped Chapters 19 & 20 from me, won't link to that gallery. :P (Sorry if it sounded petty, but the same hack tried to snipe another story I upload, though in the end I managed to have his gallery expunged -- maybe it helped that I received the blessing of the original creator.
@ stray_catz I cannot, as my internet connection's upload speeds are terrible. :(
@ 2generic Yes, pretty much. I was able to catch his farewell post on pixiv before he deleted his account: he stayed online for a bit to answer questions from commenters--and there was quite a number of them(!!). It was obvious that Astrea-san was quite popular.
There's karakara8 (https://www.pixiv.net/en/users/45168768) who made short animated clips of Astrea based on Defeated Warrior, with some clips from Defeated Warrior Append (which I'll be updating next), and a few from Chapter 17. I'm not planning on putting up a gallery of his work for now, especially because converting from ugoira to GIF would result in massive loss of detail, especially with the 10mb limit on GIFs. :(