ANSWER: This is Yakumo Yukari from the Touhou franchise. The artist is buckethead. Theres no video, only a pair of gifs of this character, and one more of ...

ANSWER: This is from the second episode of Sweet Home.

ANSWER: The is from an eroge called Kirari Nangoku Komugiiro ～ Shiofuki Paradise e Youkoso! ～. You can find a few more of the animated CGs on ehentai.

ANSWER: This is from an eroge called Inshoku Chikan Densha. Heres a link to the game CGs. Theres also a few videos of these gifs stitched together out ...

ANSWER: This is from the second episode of Bible Black Only.

ANSWER: This is from the second episode of Anal Sanctuary.

ANSWER: This is from the eroge Love Fetish ~Fellatio Hen~. Heres a link to the game CGs.

ANSWER: This is from the first episode of Shimaizuma.

ANSWER: The second episode of Honou no Haramase Doukyuusei.

ANSWER: This is from the fifth episode of Night Shift Nurses 2.

ANSWER: This is from Ikenai Koto.

ANSWER: This is NOT from the School Days anime. This is from the School Days eroge. Frankly, I cant find a non-torrent CG set that contains this scene. The ...

ANSWER: This is from Kamisama Dolls. Not hentai, not even ecchi really. Episode 11 if you really feel like digging out the scene.

ANSWER: This is from Pet Life.

ANSWER: This is from the eroge Pokopoko Gunsho. I cant find a non-torrent CG set that contains this gif though.

ANSWER: This is from Seikon no Qwaser II, episode 7. Not hentai but very heavy on ecchi.

ANSWER: This is from the second episode of JK to Inkou Kyoushi 4.

ANSWER: This is from Waisetsu Missile.

ANSWER: This is from Miboujin Nikki.

ANSWER: This is from the second episode of Manin Densha.

ANSWER: This is from an eroge with a stupidly long name. Heres a link to the CG set, some of them are animated. And a link to the full CG set, doesnt look ...

ANSWER: This is from Resort Boin, first episode.

ANSWER: This is from the first episode of Swing Out Sisters.

ANSWER: This is from Pet Life.

ANSWER: This is from Shinshou Genmukan, third episode.

ANSWER: This is from the first episode of Papa Love.

ANSWER: This is from the first episode of Tsugou no Yoi Sexfriend.

ANSWER: This is from the second episode of Ane Koi.

ANSWER: This is also from Shinshou Genmukan, first episode.

ANSWER: This is from Innocent: Shoujo Memoria.

ANSWER: This is from the first episode of Oppai no Ouja 48.

ANSWER: This is from the second episode of Kanojo x Kanojo x Kanojo.

ANSWER: This is from the first episode of Kakushi Dere.

ANSWER: This is from Seikon no Qwaser 2, episode 11. Not hentai, very ecchi.

ANSWER: This is from the second episode of Ikusa Otome Valkyrie G.

ANSWER: This is from Love es M.

ANSWER: This is from the second episode of Wanna SpartanSex Spermax.

ANSWER: This is from Spocon!, episode 1.

ANSWER: First episode of Kanojo x Kanojo x Kanojo.

ANSWER: Oppai Gakuen Marching Band Bu

ANSWER: @HornyDragon42 Absolutely false, I recognize those tits. This is from Oshaburi Announcer.

ANSWER: This is from the second episode of Saishuu Chikan Densha Next.

ANSWER: This is from the first episode of Shoujo kara Shoujo e.

ANSWER: This is from the third episode of Kuroinu.

ANSWER: This is in the first episode of Menkui!

ANSWER: This is from the first episode of Koikishi Purely Kiss.

ANSWER: Ane Yome Quartet, second episode.

ANSWER: Fifth episode of Joshikousei no Koshitsuki.

ANSWER: This is from an eroge called Do You Like Horny Bunnies? 2. Heres a link to a set of gifs that contain some from this eroge.