If the scene starts as fully yuri, but eventually a male comes in and joins them. (The “Male Involved” tag is only used if the male is involved from the beginning of the scene.)
Series Page
Raw Chapter Link
Rating: 3
One of the FMC’s seduces and has lesbian sex with the new girl (mostly off-screen), but they’re caught by the MC.
The MC then joins them for a threesome.
Series Page
Raw Chapter Link
Rating: 3
The MC catches the twins having lesbian sex with each other, where they immediately invite him to join them for a threesome.
Series Page
Raw Chapter Link (Pages 35-50)
Rating: 3
The two FMCs very briefly have lesbian sex with each other while their boyfriends watch before they eventually join in for an FFMM Foursome.
Series Page
Rating: 4
The FMC briefly has sex with a futanari woman while her husband watches and masturbates in the background.
In Ch. 22, the MC eventually joins them for a threesome.
Series Page
Raw Chapter Link
Rating: 3
Two ghosts disguise themselves as Harino and another guy to seduce and have an FFM Threesome with Komari.
Series Page
Video Link (Rule34 Video)
Length: Long
Stays Yuri: Male Joins + Male Watches
Rating: 4
In the good ending of Kanon’s route, Kanon has lesbian sex with Utage while the MC watches for a while.
Eventually the MC joins in and the scene turns into a threesome.
Series Page
Rating: 4
After the MC leaves the room, Doyeon and Hoobae begin to fight/have lesbian sex with each other.
The MC then returns and watches for a little bit.
This will continue into the Next Chapter, where the MC joins them for a threesome.
Series Page
Raw Chapter Link (Pages 467-471)
Rating: 2
Karin and Harumi briefly kiss each other before Harumi is taken to be raped by a group of men.
Series Page
Chapter Link
Rating: 3
Panty and Stocking very briefly have lesbian sex with each other. (No Male Scene)
Afterwards, Panty has lesbian sex with a native tribal leader. (Male Joins Scene)
Tagging this as Male Joins because immediately after this scene, Panty has sex with a horse.
Series Page
Rating: 4
Mina and Huijoo are shown having lesbian sex with each other, but they’re eventually caught by the MC.
The MC then joins them for a threesome.