Continued from the last scene, Eri and Takamine go to a karaoke place together.
Takamine then proceeds to undress and have Eri grope and 69 her.
To explain why Takamine is doing all of these things to Eri: Takamine is unsure about how the MC feels about her and how a lot of her advances have gone nowhere. She then does everything she’s done to the MC on Eri, so she can get the full picture. So this is supposed to be a demonstration, not Takamine trying to seduce or have sex with Eri.
The entire time however, in Eri’s thoughts, she keeps wanting to go further and do erotic things like lick her breasts and have sex with her.
Eri then screams about how hard it was for her to resist temptations and that there’s no way the MC didn’t feel the same way.
At the end of the chapter, Eri’s girlfriend found out about the whole thing and proceeds to punish her.