Jogakkou de Otoko Hitori na node Kousoku de Seiyoku no Hakeguchi ni Sareru Nichijou – Chapter 4 Scene 2

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Chapter Link (Pages 51-64)
Rating: 4

The MC has a foursome with Aoi, Lilliana and Midori.

On Pages 54 & 57, Aoi and Midori are briefly shown having lesbian sex in the background while the MC was having sex with Lilliana.

The MC quickly rejoins afterwards, so it remains a foursome for the rest of the scene.

InCha na Ore ga Madougu o Tsukatte Share House de Harem o Tsukutte Mita. – Chapter 13

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Chapter Link
Rating: 4

While the MC is having sex with Shieri, Rin and Ann briefly join in by groping Shieri.

While they’re sucking on her breasts, 1 of them mentions how they did this all the time in the past, implying they’ve had lesbian threesomes before.

Eventually Rin and Ann stop to just have lesbian sex with each other in the background.

So I’m gonna tag this as Male Involved, but the MC doesn’t do anything with Rin and Ann after they leave to have lesbian sex.

Her Toy Shop – Chapters 32-35

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Chapter Link
Rating: 5

Eunice takes the MC to meet her OBGYN friend, Selena. Selena uses her nurse, Kim, as a demonstration for sexual education on pleasing a woman.

While doing so, Selena proceeds to finger and grope Nurse Kim, eventually revealing herself to being a lesbian.

After the demonstration was over, because Nurse Kim got very aroused, Selena tells the MC to have sex with her. Selena briefly makes out with Nurse Kim.

While the MC is having sex with Nurse Kim, Selena goes over to Eunice and kisses her, proceeding to have sex with her. Selena says “for old time’s sake,” implying they’ve had sex with each other in the past.