Okay, here's the name of the first hentais I thought of and their respective girls (They are not in order, they will appear as the story unfolds):

1 - LIVE! (337563):

- Iemoto Sena.

- Ishihara Miyu.

- Hasewaga Haru.

- Hasewaga Aki.

2 - Tachibana-san-chi no Dansei Jijou Matome Ban (203978):

- Kyouka Tachibana.

- Yuka Tachibana.

- Koharu Tachibana.

3 - HOW I GOT MYSELF A HAREM OF FUCKBUDDIES (452217) and (484410):

- Rina.

- Megu.

- Mio.

- Yuka Tanijiri.

4 - MASTER PIECE:

- Tsubakihara Mira.

- Tsubakihara Nina.

- Tsubakihara Yuna.

5 - OneShota Byoutou 24-ji Harem Nyuuin Seikatsu (393619):

- Haru Kishiba.

- Marika Kagae.

- Naomi Hatane.

- Sayaka Chuuganji.

6 - Katekano (211173):

- Kaori Ichijou.

- Kana Ichijou.

- Reika Ichijou.

(Maybe more)

7 - Ikinari Harem Life:

- Katagiri Rin.

- Sanada Natsumi.

- The Sensei (The hentai didn't mention her name so I'll invented one in a near future)

- Tojo Saki.

- Ninomiya Yuuka.

8 - Kemomimi Onsen (54242):

- Miku.

- Komugi.

- Wakaba.

9 - Kokujin no Tenkousei NTR ru (339019):

- Nao Michiba.

- Michiru Mori.

- Kaede Mori.

- Ayumu Shiina.

10 - Yarichin kara Imouto to Osananajimi no Honnou Mukidashi na Shashin o Katte Shikoru Hon (502226):

- Natsuka Hinataji.

- Yumina Isumi.

11. Danmachi (But not the anime, it will be a Danmachi world from a hentai) 

- Hestia.

- Ais.

- Lily.

Name of the doujin: Is It Wrong to Try to Have Sexual Intercourse in a Dungeon? 

12. Momoiro Nurse (150145)

- Ayano.

- Usami.

- Atsuko Fujimura.

- Shiraishi.

- Takase.

13. Youkoso! Sukebe Elf no Mori e The Animation 

- Nol.

- Lucie Menelumia.

- Phyllis Hagerhelm.

- Misery Stentrem.

- Evelyn Celebrían.

- Delva Celebrían.

- Elda Ballad.

14. Yukikaze Taimanin (There are so many codes that I can't put all of them, sorry)

- Shiranui Mizuki.

- Mizuki Yukikaze.

- Rinko Akiyama.

- Shinganji Kurenai.

- Felicia.

- Astaroth.

- Koukawa Asuka.

- Igawa Asagi.

- Igawa Sakura.

- Lilim.

- Minasaki.

- A few more that I'll add in the future, ¿why? Because other than the first three and the last two, the rest I have no idea who they are, so I'll have to investigate them and it'll take me some time to do, sorry for the inconvenience.

- Please tell me more because there are a lot and I don't know how many add, so tell me your favourite ones, plase.

15. Enjo Kouhai (203189) (This is the first chapter code, I won't put more because there are 10, so search by yourself, from this code is easy)

- Iris Thea Eaderlindt.

- Aegis Thea Eaderlindt.

- Ursula Y Ddraig.

- Elliot Leucosia.

- Ouka Origamine.

16. Gokinjo Sugi SeFri

- The mother (In the hentai her name is never mentioned so we call her... Kaori)

- Miki.

- Natsuki.

- Mifuyu.

- Hayamizu Sonoka.

- Ohashi Sayuki.

- The other milf is very... bitch, tell me if you want to put in the protagonist's harem, I don't want to put her here but if you want... tell me.

17. LoveCome Shujinkou Ga Tomodachi (1143243) (This isn't in nhentai, you have to put this code in imhentai)

- Yuka.

- Natsuka.

- Misaki.

- Yuzuki.

- Yui.

- Yui's mother (We'll call her... Madoka)

18 - Maotoko-kei Heroine Kanotto-kei Onnaaruji-kaku (496199)

- Rino Kato.

- Miyu (Maybe, I don't know yet)

19 - To Aru Majustsu No Index or Railgun (I'm searching for one, but If I don't find anyone, I'll invent one)

- Shirai Kuroko.

- Index.

20 - Genshin Impact (392008)

- Klee

- Nahida

- Maybe more

21 - InCha Couple ga You Gal-tachi to SEX training Suru Hanashi (513539)

- Suzume Kagami.

- Sayu Wakaba.

- Fuchise Sumire.

- Suzuki Momo.

- Wakaba Chisa.

22 - Konosuba (477945)

- Aqua.

- Maybe more.

23 - Sword Art Online (117942)

- Keiko Ayano (Silica)

24 - Daigaku Debut de Hatsutaiken (341633)

- Aoi-chan

25 - Idol Sister (Hentai): 

- Ayaka Takano

- Maki Kamii

- Maina Oizumi

*Note: Don't worry about yuri, read the synopsis if you have doubts.