Artist patron site: https://fantia.jp/fanclubs/7219 and https://enty.jp/decoyen
Pixiv: https://www.pixiv.net/member.php?id=82301

There's a basic introduction to the Magical Student series here: https://e-hentai.org/g/1235006/6d446f4bb0/
Yuko appears in the following doujins:
https://e-hentai.org/g/891015/a617ab447d/ (Magical Student Alice 6)
https://e-hentai.org/g/1121687/c76bf7f656/ (noa)
https://www.pixiv.net/member_illust.php?mode=medium&illust_id=62964910 (West 1)
https://www.pixiv.net/member_illust.php?mode=medium&illust_id=67040890 (West 2)
In the most recent comic she has been killed briefly and resurrected in a new costume.[to be uploaded later]

-DESCRIPTION-
Yuko's magical girl form from what I've guessed, favours guns and is useless in close combat. Yuko's normal attire is usually either a black or a white school uniform. She can't get pregnant in her magical girl form but is vulnerable in her normal form.

Artist's description from google translate:
"Yuko (15) ... JC heroine, commonly known as "junior combination." We can not activate abilities of weapons without weapons, so weapons are distributed from organizations and they are always carried around."

-CONTENTS-
(all guesswork from google translate)
p1-5: Character sheets
p6-9: The events of Magical Student Alice 6 (linked above), with alternate bad end
p10-16: Events of Magical Student Alice 6, a different bad end. mos noted that they are all getting pregnant here.
p17-20: This story is called "Careless". While being raped, Yuko tries to avoid pregnancy, by transforming back to a magical girl at the moment of ejaculation. Doesn't work.
p21-22: A big frog man takes hostages and forces Yuko to strip.
p23-24: Yuko tries to save someone with bullets + bad end if she doesn't succeed
p25-27: Beaten and taken away to a monster's hideout. Undergoes quite an ordeal before rescue
p28-29: Tricked by a child and then chained up.
p30: Yuko and Miri out shopping.
p31-34: Yuko and Miri captured by the "shower caps"
p35-37: A tentacle monster.
p38-41: Fighting zombies
p42-51: Excerpt from Magical Student West 3. Fighting the scary clown from West 2.

OTHER CHARACTERS:
https://e-hentai.org/g/1263404/24f1edaa45/ (Shea)
https://e-hentai.org/g/1256909/4896705cd4/ (Asuka)
https://e-hentai.org/g/1235006/6d446f4bb0/ (Character Guide)